ery varying from well rounded to feebly, obsoletely angled in the various subspecies. Base umbilicated, well rounded, usually sculptured like the upper portion of the last whorl. Aperture subcircular; outer lip reflected and expanded; inner lip strongly curved and decidedly excavated; parietal wall narrow, covered with a thin callus. Operculum membranaceous. The size of the shell varies from the huge Leptopoma nitidum guimarasensis from Guimaras Island, to the small Leptopoma nitidum ancilis from Cebu. The character of the incised spiral sculpture, particularly that of the last whorl, enables one to separate this complex into three distinct groups. In the first of these, the incised lines are deep and rather distantly spaced. This group embraces, L. n. siquijorensis from Siquijor Island, L. n. guimarasensis from Guimaras Island, and L. n. darajuayensis from Darajuay Island. The second group has the incised spiral sculpture of the same strength as in the first group, but the striations are more closely placed and these, in connection with the lines of growth, are so arranged as to give the surface of the last whorl the appearance of a cloth-like texture. There are seven subspecies belonging to this group, L. n. atropos from Polillo Island, L. n. cebuensis, from Cebu Island, L. n. butauananensis from Butauanan Island, L. n. basiaoensis from Basiao Island, L. n. maculaboensis from Maculabo Island, L. n. leytensis, from Leyte, and L. n. nitidum from northern Luzon. Of these, the first three have an obsolete spiral thread at the periphery while the last four have this portion of the shell evenly rounded. It is interesting to note that in some of these forms the spiral lirations characteristic of the nepionic whorls of all the members of the nitidum group, extend beyond the nepionic portion of the shell. In the third and last group, the spiral sculpture is feeble and consists of feebly incised, wavy lines. This group embraces five subspecies, L. n. romblonensis from Romblon Island, L. n. panayensis from Panay Island, L. n. anaitis from Cebu, L. n. unionensis from Luzon, and L. n. artemisia from the small island of Panay, of the Catanduanes Group, off Eastern Luzon. Key to the subspecies of Leptopoma nitidum Sowerby Spiral sculpture consisting of strong, deeply incised lines. Spiral striations distantly spaced on the last whorl. Nepionic whorls brown. 1. siquijorensis Shell more than 20 mm. in diameter... 2. guimarasensis Umbilicus more than half covered.. 3. darajuayensis Spiral striations closely spaced on the last whorl. Spiral lirations confined to the nepionic whorls 5. atropos Spiral lirations not confined to the nepionic whorls. Umbilicus more than half covered..... 6. cebuensis Umbilicus less than half covered.. 7. butauananensis Obsolete peripheral thread absent. Spiral lirations confined to the nepionic whorls. 8. basiaoensis 9. maculaboensis Umbilicus more than half covered. . 10. leytensis Shell less than 15 mm. in diameter. 11. nitidum .12. romblonensis Spiral sculpture consisting of weak, feebly incised lines. 13. panayensis Spiral lirations confined to the nepionic whorls. Shell less than 16 mm. in diameter.. 14. anaitis 15. unionensis 16. artemisia The type locality, measurements, and disposition of the types are shown in table 1. All of the above subspecies excepting number 11, L. n. nitidum Sowerby, are new. ABSTRACTS Authors of scientific papers are requested to see that abstracts, preferably prepared and signed by themselves, are forwarded promptly to the editors. The abstracts should conform in length and general style to those appeariug in this issue. RADIOMETRY.-The photo-electric cell and other selective radiometers. W. W. COBLENTZ. Bur. Stand. Sci. Paper., No. 319. Pp. 29. 1918. This paper deals with the application of special physical and chemical properties of matter, as a means of quantitatively measuring radiant energy. Certain substances have the property of decreasing in electrical resistance when exposed to radiant energy of short wave-lengths, especially the visible and ultra-violet rays. Crystalline selenium belongs to this class of substances. The sensitivity of the selenium cell varies not only with the wave-length but also with the intensity of the light stimulus; and it recovers but slowly from the effects of the light stimulus. It therefore fails to meet the requirements of a radiometer, except that of high sensitivity. The application of the photo-chemical action upon a photographic plate, as a means of making quantitative radiometric measurements is considered. While this method of radiometry has been used successfully, its applications seem to be rather limited. The alkali metals, and especially their hydrides, are very sensitive to light stimuli. Photo-electric cells made of these substances can be constructed and operated so that the response (photo-electric current released) is proportional to the intensity of the stimulus. This meets one of the principal requirements of a satisfactory radiometer. Details of constructions, operation, and characteristics of the photo-electric cell are given, and a satisfactory, high-resistance, iron-clad Thomson galvanometer is described, which may be used successfully with the photo-electric cell. The advantages of the photo-electric cell over the thermopile are considered and the application of the former is advocated for measurements of radiant energy (especially ratios of intensities) in the violet and ultra-violet parts of the spectrum, where the photo-electric cell greatly exceeds the thermopile and the bolometer in sensitivity W. W. C. METALLURGY.-Copper. Bur. Stand. Circ. No. 73. Pp. 103. 1918. A compilation is given of the most accurate published information. concerning the physical and mechanical properties of the metal copper, together with data and discussion on the effect of higher and lower temperatures upon the physical properties as well as that of impurities in the metal. The circular is concluded with a comprehensive bibliography of the subject, and some typical standard specifications for the metal in different forms. This circular is one of a series dealing with properties of metals and alloys. GEOLOGY.-The Quaternary geology of southeastern Wisconsin, with a chapter on the older rock formations. WILLIAM C. ALDEN. U. S. Geol. Survey Prof. Paper 106. Pp. 356, with 39 plates and 21 . figures. 1918. areas. This report treats of the southeastern quarter of the State of Wisconsin, an area of more than ten thousand square miles. The main interest of this paper may be said to center in the phenomena developed by the Green Bay glacier and their relations to surrounding The topographic control of glacial flow is illustrated by many interesting features. On the east this glacier, after surmounting the Niagara escarpment, met the lateral flow of Lake Michigan, glacier head-on and the great interlobate Kettle Moraine was formed. the south the Green Bay ice spread with typical radial flow over the eroded surface of an older drift sheet. It developed a remarkable system of radiating drumlins, with eskers, outwash plains, and recessional moraines. On the west the glacier encroached on the Driftless Area and the relations of the ice to a well-marked erosion topography may be studied in detail. At The Paleozoic rock formations are mapped and described, physiographic development and preglacial topography are discussed, and the configuration of the bed rock and its relations to the many beautiful lakes and the present drainage system are shown on a map. The glacial phenomena are illustrated by one of the finest maps of glacial deposits ever published. This map, on a scale of about 4 miles per inch, shows in colors the relations of the various drift features to the drainage and roads of each township. The report and accompanying maps should be of interest to general and scientific readers and be of great value to the schools and colleges of Wisconsin and other states. W. C. A. |