near which it seems to be a little gaping; base somewhat straightened, or even a little sinuous in outline, just in front of the middle, at the termination of a broad, very shallow concavity extending obliquely downward and backward from the umbonal region; behind this rather prominent, thence ascending obliquely, with a slightly convex outline, to the truncated posterior margin. Posterior umbonal slopes very prominently rounded above, and continued as a low, undefined ridge, obliquely backward and downward; posterior dorsal slope, above the umbonal ridge, with an oblique, shallow, rounded sulcus, extending from the back part of the beaks to the middle of the truncated margin behind. Surface marked with fine lines of growth and small, irregular, concentric wrinkles, which latter are not defined on the posterior dorsal region above the umbonal ridge; crossing these are the usual radiating rows of minute granules. (Meek.) Horizon and localities.-Upper Carboniferous, Upper Coal Measures: Kansas City. Allorisma subcuneatum MEEK & HAYDEN. Allorisma subcuneatum Meek & Hayden, 1858: Proc. Acad. Nat. Sci., Phila., p. 263. Allorisma ensiformis Swallow, 1863: Trans. St. Louis Acad. Sci., vol. I, p. 656. Allorisma subcuneatum Meek & Hayden, 1864 Pal. Upper Mo., p. 37, pl. i, figs. 10a-b. Allorisma subcuneatum Geinitz, 1866: Carb. und Dyas in Nebraska, p. 76. Allorisma subcuneatum Meek, 1872: U. S. Geol. Sur. Nebraska, p. 221, pl. ii, figs. 13a-b. Shell large, two or three times as long as high, with greatest breadth in front of the middle, gaping slightly behind. Upper border nearly straight, flattened immediately behind the beaks so as to form a long lanceolate area, with subangular margins; between these angularities and the low, scarcely defined umbonal ridges there is a narrow, shallow depression in each valve. Basal margin nearly parallel to dorsal, slightly curved. Anterior border short, regularly rounded, a little gaping. Beaks large, prominent, incurved, and placed well for ward. Surface marked only by low concentric folds and fine lines of growth. Horizon and localities-Upper Carboniferous, Upper Coal Measures: Kansas City. Solenopsis solenoides (GEINITZ). Clidophorus solenoides Geinitz, 1866: Carb. und Dyas in Nebraska, p. 25, tab. ii, fig. 7. Solenopsis solenoides Meek, 1872: U. S. Geol. Sur Nebraska, p. 223, pl. x, fig. 3. Shell small, rather compressed, elongated, the length being about four times the height, narrowing posteriorly; cardinal margin nearly straight, erect, less than the entire length of the valves, with a faint external compression or shallow furrow just below it; basal margin broadly convex in outline, the most prominent part being in advance of the middle; beaks much depressed and compressed, or scarcely distinct from the cardinal margin, placed within about one-eighth the entire length of the shell from the anterior extremity, and defined in front by a short vertical indentation; anterior side narrowly rounded, or with the upper side sometimes faintly truncated, with a slight slope from the little indentation forward. Surface with fine, regular striæ of growth, which are nearly or quite obsolete, excepting on the lower half of the valves. Horizon and localities.-Upper Carboniferous, Upper Coal Measures: Kansas City. Chænomya minnehaha (Swallow). Allorisma minnehaha Swallow, 1858: Trans. St. Louis Acad. Sci., vol. I, p. 193. Chænomya minnehaha Meek & Hayden, 1864: Pal. Upper Mo., p. 43. Chonomya minnehaha Meek, 1872: U. S. Geol. Sur. Nebraska, p. 217, pl. ii, figs. 13a-b. Shell of medium size, obliquely elliptic in outline, ventri cose; anterior border rather sharply rounded above; posterior margin truncated, narrowly curved below, gaping broadly; cardinal border curved. Beaks rather prominent, depressed, somewhat incurved, and well forward. Posterior umbonal slopes prominent. i Horizon and localities -Upper Carboniferous, Upper Coal Measures: Kansas City. Chænomya leavenworthensis (MEEK & HAYDEN ). Allorisma leavenworthensis Meek & Hayden, 1859: Proc. Acad. Nat. Sci., Phila., p. 263. Chænomya leavenworthensis Meek, 1861: Pal. Upper Missouri, p. 43, pl. ii, figs. la-c. Chænomya leavenworthensis Meek, 1872: U. S. Geol. Nebraska, p. 216, pl. ii, fig. 9. Somewhat smaller than C. minnehaha, and having the beaks set farther back than in that species. Horizon and localities.-Upper Carboniferous, Upper Coal Measures: Kansas City. Cardiomorpha triangulata SWALLOW. Cardiomorpha triangulata Swallow, 1860: vol. I, p. 655. Trans. St. Louis Acad. Sci., Somewhat larger than C. missouriensis, and more triangular in outline. Horizon and localities-Lower Carboniferous, Chouteau (Kinderhook) limestone: Cooper county. Cardiomorpha missouriensis SHUMARD. Cardiomorpha missouriensis Shumard, 1858: Trans. St. Louis Acad. Sci., vol. I, p. 207. Shell small, like an Allorisma in general appearance, but having larger umbonal regions. Horizon and localities.-Upper Carboniferous, Lower Coal Measures: Charboniere (St. Louis county), Lexington (Lafay ette county). Spurious and Doubtful Species. Allorisma cuneata Swallow, 1858: Trans. St. Louis Acad. Sci., vol. I, Aviculopecten williamsi Meek, 1871: Proc. Acad. Nat. Sci., Phila., p. 178. Cardium lexingtonensis Swallow, 1858: Trans. St. Louis Acad. Sci., vol. I, p. 206. Coal Measures: Lexington. Poorly defined. Cypricardinella gorbyi Miller, 1891: Geol. Sur. Indiana, 17th Ann. Rept., Adv. sheets, p. 92. Keokuk limestone: Boonville. Probably synonymous with species already described. Cypricardia plicatula Swallow, 1858: Trans. St. Louis Acad. Sci., vol. I, p. 205. Coal Measures: Platte county. Cannot be recognized. Cypricardia pikensis Swallow, 1863: Trans. St. Louis Acad. Sci., vol. II, p. 95. Coal Measures: Pike county. Poorly defined. Cypricardia occidentalis Swallow, 1863: Trans. St. Louis Acad. Sci., vol. II, p. 96. Not recognizable. Cypricardia chouteauensis Swallow, 1863: Trans. St. Louis Acad. Sci., vol. II, p. 96. Chouteau limestone: Cooper county. Described insufficiently. Edmondia marionensis Swallow, 1860: Trans. St. Louis Acad. Sci., vol. I, p. 654. Chouteau limestone: Cooper county. Cannot be identified. Grammysia blairi Miller, 1891: Geol. Sur. Indiana, 17th Ann. Rep., Adv. sheets, p. 93. Chouteau limestone: Sedalia. Probably identical with forms already described. Isocardia curta Shumard, 1858: Trans. St. Louis Acad. Sci., vol. I, p. 206. Coal Measures: Charboniere. Cannot be recognized. Macrodon micronema Meek & Worthen, 1866: Proc. Acad. Nat. Sci., Phila., p. 261. Kaskaskia limestone: Ste. Genevieve county. Cannot be recognized. Pernopecten sedaliensis Miller, 1891: Geol. Sur. Indiana, 17th Ann. Rep., Adv. sheets, p. 93. Chouteau limestone: Sedalia. Too imperfect for recognition. Solen missouriensis Swallow, 1860: Trans. St. Louis Acad. Sci., vol. I, p. 655 Poorly defined. CHAPTER XIII. GASTEROPODS. Dentalium primarium BALL. Dentalium primarium Hall, 1858: Geology Iowa, vol. I, p. 666, pl. xxxiii, fig. 16. Shell large, stout, nearly straight; surface smooth. Horizon and localities-Lower Carboniferous, Keokuk limestone: Warsaw (Illinois). Dentalium missouriense SWALLOW. Dentalium missouriense Swallow, 1863: Trans. St. Louis Acad. Sci., vol. II, p. 99. Shell rather large, thin, slightly curved, and marked with small longitudinal ribs. Horizon and localities.-Lower Carboniferous, Kaskaskia limestone: Ste. Mary (Ste. Genevieve county). Dentalium meekianum GEINITZ Dentalium meekianum Geinitz, 1866: Carb. und Dyas in Nebraska, p. 13, t. i, fig. 20. Dentalium meekianum Meek & Worthen, 1873: Geol. Sur. Illinois, vol. V, Proc. Acad. Nat. Sci., Phila., p. 234. p. 590, pl. xxix, figs. 8a-c. Dentalium meekianum Keyes, 1838: Dentalium meekianum Keyes, 1891: Shell rather small, curved, subcylindrical, ornamented by numerous fine oblique lines. Horizon and localities.-Upper Carboniferous, Upper Coal Measures: Kansas City. In the Carboniferous rocks of the Mississippi basin, four distinct types of Dentalium are recognized. The first has the surface ornamentation composed of a series of ridges trans |