Thermodynamic Laws. While the book is free of the engineering slant of the preceding volume on Electricity it lays an excellent foundation for Heat Engineering. F. E. B. 8. Matter and Motion; by J. CLERK MAXWELL. Pp. x, 163. London, 1920 (Society for Promoting Christian Knowledge).— The present interest in the foundations of Mechanics makes this an opportune time for a new printing of Maxwell's well known little treatise on the principles of dynamics. It is edited by Sir Joseph Larmor who has added notes, a chapter on the Equations of Mition of a Connected System from the author's Electricity and Magnetism, and two appendices. The first of these treats of the Relativity of the Forces of Nature. The editor's discussion of the Einstein theory is given from a refreshingly detached point of view compared to the dogmatism of its avowed protagonists. The second appendix develops the wider aspects of the Principle of Least Action. The book is further enriched by the reproduction of a hitherto unpublished portrait of Maxwell. F. E. B. 9. Mechanical Sciences Tripos; Pp. 57. Cambridge. 1920 (Cambridge University Press).-A pamphlet containing reprints. of the papers set in Applied Mechanics, Heat and Heat Engines, Theory of Structures, and Electricity, during the years 1912, 1913, 1914, 1915, and 1919. They contain a mine of suggestions for teachers who may desire to test the proficiency of honor students. F. E. B. 10. A Text Book of Physics; by W. WATSON. Pp. xxvi, 976, London, 1920 (Longmans, Green & Co.).-Extended treatises on Physics in English such as are available in German or in French do not exist, but that there is a considerable demand for a full one volume text is evidenced by the issue of a seventh edition of Watson's Physics. Notices of the second and the fifth editions have already appeared in this Journal (see 9, 296, 1900 and 35, 104, 1913). After the death of the author in war service, the revision was entrusted to H. Moss, lecturer in Physics at The Imperial College of Science and Technology of London, who has corrected the values of the more important physical constants, and supplied material for some of the lacunae which existed in the earlier editions. The new matter amounts to twenty-three pages distributed over thirty or more topics, among which may be noted: the McCleod gauge, Moduli of Elasticity, Callendar's constant pressure air thermometer and the constant flow calorimeter, sound ranging, the interferometer, the echelon grating, Gauss's theorem, Kirchhoff's laws, the d'Arsonval galvanometer, parallel connection of condensers, A. C. equations, and reflections of X-rays. A conspicuous omission is any reference to crystal detectors, or to the thermionic vacuum tube. Possibly room should also have been found for the resolving power of a prism. The book as a whole is to be commended as one which not only the student but any reader would be glad to possess. II. GEOLOGY. F. E. B. 1. The Crinoidea Flexibilia; by FRANK SPRINGER. Smithsonian Institution Pub. No. 2501, two vols., text and plates, 486 pp.. 79 pls., 51, text figs., 1920.-In these two grand volumes we have the results of a long labor of love by an able lawyer, a work made possible largely through his own financial resources and paleontologic ability, though he works at Washington in a most stimulating environment and in an institution that will always fully appreciate the gift of his great collections. The printing and paper of the monograph are of the best and the heliotype plates well reproduce the very beautiful and accurate drawings of Mr. Georg Liljevall, of Stockholm, and Mr. K. M. Chapman, of Sante Fe. Wherever crinoids occur, there the author, or others for him, have gone and labored long to get these usually rare fossils. These co-workers he loves as much as his adopted children, the Echinoderma, and on pages 8 to 15 and in places throughout the text he writes feelingly and interestingly of their help and talent. The volumes are dedicated to the man who started him on his career in paleontology, Charles Wachsmuth, "collaborator and friend of early years. It is interesting to note that the Silurian of Decatur County, western Tennessee, has yielded as great a variety of crinoids as that of the Swedish island of Gotland, and that they exhibit “in. some respects a remarkable parallelism with the Gotland fauna,” while the Laurel limestone of Indiana bears a similar striking resemblance (p. 15). Both American areas got their faunas through what is now the Gulf of Mexico embayment. While the author's method of study is in the main morphologic, yet the fossil forms are also studied in the light of the recent crinoids. He tells us that of living forms there are now described 567, with about 50 new ones to be defined, and that the U. S. National Museum has no fewer than about 350 species represented by 5,387 specimens. This great collection of recent crinoids has been built up largely by Doctor Austin H. Clark, with the backing of Mr. Springer. Close attention is also given to the ontogenetic stages in living genera, and many of these stages (in 5 genera) are figured from drawings by H. E. Wilson on the three first plates. In Comactinia meridionalis from off Yucatan there is retained a longer series of development stages than is commonly present, and the study of this species leads the author to conclude that there is "in the ontogeny of this living crinoid an unusually close recapitulation of the phylogenetic history of some of the Paleozoic groups of the class" (86). The Taxocrinidae "represent the true Flexibilia type," and are "comparable to stages in the ontogeny of living crinoids" (96). On pages 402-403 is described a remarkable case of "recuperation," where a specimen of Taxocrinus colletti regenerated an entire crown from the infrabasals and one basal, indicating that "the seat of vitality was lodged low down within the infrabasals." For twenty years, Springer has been gathering Crinoidea Flexibilia and now he presents all the morphologic and geologic detail of the 176 known species (54 new) in 31 genera (4 are new, but Springer is the author of 13). Of these, 109 are American, the remainder European. They begin in the Ordovician with 2 forms, differentiate quickly in the Silurian, where 71 are known, 34 occur in the Devonian, 68 in the Mississippian, and the order dies out in the early Pennsylvanian, where but a single species is known. Besides, the author treats in the same detail 6 other genera (Incertae sedis). that have been referred on insufficient grounds to the Flexibilia, one of which is the curious Edriocrinus with 9 species (4 new) that are attached by the calyx to foreign objects, in this suggesting the recent Holopus. The author's principle of classification is morphologic and not phylogenetic, and the order Flexibilia is said to be "an offshoot. from the dicyclic Inadunata. . . through the non-pinnulate Dendrocrinidae" (88). This took place early in the middle Ordovician, in fact, it was at this time that most of the ordinal differentiation of the crinoids from the cystids occurred. Springer says: "Thus it seems that at this very early stage in the geological scale we have forms exhibiting variously intermingled characters of the larger divisions of the crinoids, with some of the essential cystid structure more or less impressed upon one of them; and that these represent relatively recent departures from the common ancestral type, tending in different degrees toward the lines of evolution which produced the several orders of the crinoids. In Protaxocrinus the Flexible characters were already well established; in Cupullocrinus and Reteocrinus the tendency was toward the Inadunata and Camerata respectively, while still complicated by other characters; while in Cleiocrinus the strong survival of cystid characters prevented the establishment of a distinct evolutionary line in either of the crinoidal orders" (91). Springer maintains that with our present knowledge crinoids are best classified into four orders, as follows: (1) Inadunata, having generalized forms ranging from the Ordovician to Recent; (2) Flexibilia, having more or less specialized Paleozoic genera; (3) Camerata, with highly specialized forms; and (4) Articulata, the latest derived crinoids, beginning in the Jurassic and extending into Recent times. We congratulate Doctor Springer on the completion of this monumental work, one of the best paleontologie monographs yet published in America, and we look forward with much expectation to the several other works he announces. C. S. 2. The Dunkard Series of Ohio; by C. R. STAUFFER and C. R. SCHROYER. Geol. Survey Ohio, 4th ser., Bull. 22, 167 pp., 13 pls.. 1 map, 1920.-In this very detailed account of the stratigraphy of the terminal deposits of the Paleozoic of Ohio, the Upper Barren of the older reports, known since 1891 as the Dunkard series, is placed at the bottom of the Permian system, in conformity with general usage. There is no general break between the Pennsylvanian and Permian. The series has a distribution in Pennsylvania, West Virginia, and Ohio of about 8,000 square miles; in the last-named state it is now known to cover about 1,213 square miles to the north and west of the Ohio River from Wheeling to Pomeroy. The thickness in Ohio is about 600 feet, in Pennsylvania from 900 to 1,000 feet, but originally the Dunkard must have been considerably thicker, It consists in the main of sandy shales, interspersed with more or less persistent sandstones (about 9, having variable thicknesses that at times attain to about 35 feet), with impure limestones (5, usually thin but locally up to 16 feet thick), and with thin coals (6, only one thick enough to mine, but that one 5 to 7 feet thick in places). In this way the series is divided into 22 named zones. In Ohio, the sandstones of the Dunkard are sometimes conglomeratic and sun-cracked, more often the quartz is sharp in grain, cross-bedded, rippled, and nearly always micaceous; in Pennsylvania, they are more or less feldspathic. The shales are red in the upper part and in places the whole series is of the same color; locally occur selenite crystals or traces of gypsum. The limestones are more or less muddy and probably all of fresh-water origin, since the only unmistakable marine fossil is Lingula permiana, n. sp., a small form restricted to a black shale associated with one of the coal beds. Even though all the invertebrates are described as new species, and most of them referred to marine genera, they are thought to be probably forms living in fresh water or on the land. All are small, and most of them exceedingly so. They include 4 bivalves, 3 gastropods, Spirorbis, and ostracods. In addition, there are fish scales and ganoid teeth, at least one large dorsal shark spine, the dorsal spine of a reptile (Edaphosaurus), and coprolites. At the base of the Dunkard occurs the Cassville shale, which in West Virginia has yielded a Permian flora of 107 species, and a number of cockroach wings; in Ohio, however, only 21 plant species have been noted. The reviewer gets the impression from the book that the climate of Dunkard time was still warm, though tending to become more and more arid, that the gradually subsiding coastal swamp area of the Dunkard lay near sea-level, and that but rarely did the sea back water far into the region of this earliest of Permian depositions. The report is especially valuable for any one who wishes to dig out the environmental conditions of the time through the detailed presentation of the many local exposures. C. S. 3. The Stratigraphy and Paleontology of Toronto and Vicinity, Part I, The Pelecypoda; by BEATRICE HELEN STEWART. Twenty-ninth Ann. Rept., Ontario Dept. Mines, pp. 1-59, 5 pls., 1920. It is interesting to note the revival of interest in the local paleontology of the strata about Toronto. It is proposed first to describe the later Ordovician faunas and then modernize the correlation in accordance with the sequences elsewhere. In Part I are described 59 species of bivalves, of which 53 are specifically determined, and 11 are new. C. S. 4. Notes on the Geology and Oil Possibilities of the northern Diablo Plateau in Texas; by J. W. BEEDE. Univ. of Texas Bull. No. 1852, 40 pp., 7 pls. (1 geol. map), 2 text figs., 1918 (1920).— This report is valuable not only for what it describes, as indicated in the title, but for the discovery it records of a Chester fauna (the Helms group of strata, 400-600 feet thick) beneath the Pennsylvanian-Permian. There is also a very valuable correlation table synchronizing the various areas of the late Paleozoic formations of Texas with those of Oklahoma and Kansas. The stratigraphy of Texas is advancing with leaps and bounds, and the State Survey is to be congratulated on the rapid progress made. C. S. 5. The Weno and Pawpaw Formations of the Texas Comanchean; by W. S. ADKINS, and On a new Ammonite Fauna of the Lower Turonian of Mexico; by EMIL BÖSE. Univ. of Texas Bull. No. 1856, 257 pp. (quarto), 20 pls., 20 text figs., 1918 (1920).— In the first part of this memoir are described the two formations named in the title, and their distribution is traced throughout the state. Their faunas consist of 69 forms, of which 51 are named specifically. Of new species there are 29. Of ammonites there are more forms than is usual in the Lower Cretaceous of America. The second part of the memoir describes an interesting but small assemblage of invertebrates, chiefly ammonites, that occurs near the base of the American Upper Cretaceous in northern Mexico. Of species studied there are 21, but only 8 are specifically determined, 7 of these being new. The affinities of these forms are clearly with those of the Mediterranean Turonian. C. S. Fossil Corals from Central America, Cuba, and Porto Rico, with an account of the American Tertiary, Pleistocene, and Recent Coral Reefs; by THOMAS WAYLAND VAUGHAN. U. S. Nat. Mus., Bull. 103, pp. 189-524, pls. 68-152, 1919.-In this memoir is painstakingly brought together all that is known of the Cenozoic corals within the area of the Caribbean Sea and the Gulf of Mexico. There are about 142 forms, 78 of which are new, and they are divided among 40 genera. It is quite evident that it is now very difficult to identify either recent or fossil corals, since their classification is dependent upon constantly changing calcareous structures. The coral animals are very sensitive to their environment, and this must be known in order to classify them expertly. In stratigraphy, the author does not rely on single forms for age determinations, but whenever possible, on a combination of associated forms. In this connection he directs attention to the 54 forms of corals living within one half mile of each other on Cocos-Keeling islands in the lagoon (23), in the |