410 



GASTEROPODA. 



[MIC. MUR. 



barabuensis, Whitfield, 1878, Ann. Eep. 

 Geo. Sur. Wis., p. 60, and Geo. Wis., 

 vol. 4, p. 195, Low. Magnesian Gr. 

 billingsi, Walcott, 1883, 35th Rep. N. Y. 

 Mus. Nat. Hist., p. 212, Trenton Gr. 



FIG. 685. Metoptoma canadensis. a, Upper 

 side ; ft, side view ; c, under side. 



canadensis, Billings, 1865, Pal. Foss., vol. 



1, p. 394, (Chiton canadensis,) Black 



Riv. Gr. 

 cornutiformis, Walcott, 1879, Desc. New 



Spec. Foss., p. 1, Calciferous Gr. 

 devonica, Walcott, 1885, Monogr. U. S. 



Geo. Sur., vol. 8, p. 195, Devonian, 

 dubia, Hall, 1847, Pal. N. Y., vol. 1, p. 23, 



Chazy Gr. 



erato, see Tryblidium erato. 

 estella, Billings, 1862, Pal. Foss., vol. 1, p. 



153, Hud. Riv. Gr. 

 eubule, see Tryblidium eubule. 

 hyrie, see Tryblidium hyrie. 

 instabilis, Billings, 1865, Pal. Foss., vol. 1, 



p. 251, Quebec Gr. 

 melissa, Billings, 1862, Pal. Foss.. vol. 1, 



p. 86, Quebec Gr. 

 montrealensis, Billings, 1865, Pal. Foss., 



vol. 1, p. 394, Chazy Gr. 

 niobe, see Tryblidium niobe. 

 nycteiz, see Tryblidium nycteis. 

 orithyia, Billings, 1862, Pal. Foss., vol. 1, 



p. 38, Calcif. Gr. 

 orphyne, Billings, 1862, Pal. Foss., vol. 1, 



p. 88, Quebec Gr. 

 peroccidens, Walcott, 1885, Monogr. U. S. 



Geo. Sur., vol. 8, p. 260, Subcarb. 

 perovalis, Whitfield, 1878, Ann. Rep. 



Geo. Sur. Wis., p. 74, and Geo. Wis., 



vol. 4, p. 211, Trenton Gr. 

 phillipsi, Walcott, 1885, Monogr. U. S. 



Geo. Sur., vol. 8, p. 83, Trenton Gr. 

 quebecensis, Billings, 1865,- Pal. Foss., vol. 



1, p. 308, Quebec Gr. 

 recurva, Whitfield, 1878, Ann. Rep. Geo. 



Sur. Wis., p. 61, and Geo. Wis., vol. 4, 



p. 196, Low. Mag. Gr. 

 retrorsa, Whitfield, 1880, Ann. Rep. Geo. 



Sur. Wis., p. 54, and Geo. Wis., vol. 4, 



p. 197, Low. Mag. Gr. 

 rugosa, see Stenotheca rugosa. 

 similis, Whitfield, 1878, Ann. Rep. Geo. 



Sur. Wis., p. 61, and Geo. Wis., vol. 4, 



p. 196, Low. Mag. Gr. 

 timplex, see Tryblidium simplex, 

 superba, Billings, 1865, Pal. Foss., vol. 1, 



p. 172, Black Riv. Gr. 

 trentonensis, Billings, 1862, Pal. Foss., 



vol. 1, p. 40, Trenton Gr. 

 undata, Winchell, 1865, Proc. Acad. Nat. 



Sci. Phil., p. 131, Kinderhook Gr. 

 umbel! a, Meek & Worth en, 1866, Proc. 



Acad. Nat. Sci. Phil., p. 267, and Geo. 



Sur. 111., vol. 3, p. 506, Burlington Gr. 



venilia, Billings, 1862, Pal. Foss., vol. 1, 



p. 88, Quebec Gr. 



MICROCERAS, Hall, 1845, Am. Jour. Sci., vol. 

 48, p. 294. [Ety. mikros, small ; keras, 

 horn.] Geueral form like Cyrtolites, 

 but distinguished by its minute size, 

 smooth surface, and less angular dorsal 

 margin. Type M. inornatxim. 



inornatum, Hall, 1845, Am. Jour. Sci., vol. 

 48, p. 294, and Ohio Pal., vol. 1, p. 147, 

 Hud. Riv. Gr. 



minutissimum, Ulrich, 1879, Jour. Cin. 

 Soc. Nat. Hist., vol. 2, p. 13, Hud. 

 Riv. Gr. 



MICRODOMA, Meek & Worthen, 1866, Proc. 

 Acad. Nat. Sci., p. 269. [Ety. mikros, 

 small; domus; house.] Shell small, sub- 

 trochiform ; volutions seven or more, 

 flattened on a line with the slope of the 

 shell; suture deep; aperture oblique; 

 surface ornamented with nodular 

 ridges. Type M. conica. 



conica, Meek & Worthen, 1866, Proc. 

 Acad. Nat. Sci. Phil., p. 269, and Geo. 

 Sur. 111., vol. 5, p. 598, Low. Coal 

 Meas. 



MURCHISONIA, D'Archiac & Verneuil, 1841, 

 B.ull. Soc. Geo. Fr., vol. 12, p. 154, and 

 Phillips Pal. Foss. Cornwall, etc., p. 101. 

 [Ety. proper name.] Shell elongated, 

 many whorled ; whorls variously sculp- 

 tured and zoned ; outer lip deeply 

 notched ; aperture slightly channeled 

 in front. Type M. bilineata. 



abbreviata, Hall, 1847, Pal N. Y., vol. 1, p. 

 32. The name was preoccupied by 

 DeKoninck in 1841. See M. subabbre- 

 viata. 



aciculata, Hall, 1860, Can. 

 Nat. and Geo., vol. 5, p. 

 154, Up. Silurian. 



acrea, Billings, 1865, Pal. 

 Foss., vol. 1, p. 232, Que- 

 bec Gr. 



ada, Billings, 1865, Pal. Foss., 

 vol. 1, p. 346, Calcif er- 

 ous Gr. 



adelina, Billings, 1865, Pal. 

 Foss., vol. 1, .p. 232, Que- 

 bec Gr. 



agilis, Billings, 1865, Pal. 

 Foss vol. 1, p. 235, Que- M u"nia 

 bee Gr. bilineata. 



alexandra, Billings, 1865, Pal. 

 Foss., vol. 1, p. 172, Black Riv. Gr. 



angulata, Phillips, 1836, (Rostellaria an- 

 gulata,) Geo. of Yorkshire, p. 230, De- 

 vonian. Very doubtfully identified in 

 America. 



angustata, Hall, 1847, Pal. N. Y., vol.1, p. 

 41, Birdseye Gr. 



anna, Billings, 1859, Can. Nat. and Geol., 

 vol. 4, p. 358, Calciferous Gr. 



archimedea, McChesney, 1861, Desc. New 

 Pal. Foss., p. 89, Coal Meas. 



arenaria, Billings, 1859, Can. Nat. and 

 Geo., vol. 4, p. 359, Calciferous Gr. 



arisaigensis, Hall, 1860, Can. Nat. and 

 Geo., vol. 5, p. 154, Silurian. 



