436 



CEPHALOPODA. 



[CYR. END. 



whitneyi, Hall 1861, Rep, of Progr. Wis., 



p. 39, Hud. Riv. Gr. 



CYRTOCERINA, Billings, 1865, Pal. Foss., vol. 

 1, p. 178. [Ety. from the termination 

 inus, signifying resemblance to Cyrto- 

 ceras.] In form 

 like a short, rap- 

 idly tapering Cyr- 

 toceras, and having 

 a large siph uncle 

 on the concave side. 

 Type C. typica. 

 mercurius, Billings, 

 1865, Pal. Foss., 

 vol. 1, p. 194, Que- 

 bec Gr. 



typica, Billings, 1865, 

 Pal. Foss., vol. 1, p. 



ewsowngcav 178 < Black Riv - Gr 



ity of siphuncle; b, Diploceras, Conrad, 1842, 



outline, side view. Jour. Acad. Nat. 



Sci., vol. 8, p. 267, 



[Ety. diploos, double; keras,- horn.] 

 Foundedupon the fragment of an En- 

 doceras, and very poorly defined. 



vanuxemi, see Endoceras vanuxemi. 

 DISCITES, DeHaan, 1825, Mongr. Ammon., 

 etc., p. 31. [Ety. diskos, quoit.] Dis- 

 coid ; umbilicus wide ; whorls quadran- 

 gular, sides flattened, and dorsum gib- 

 bous ; longitudinally striated and 

 sometimes lined transversely ; siphon 

 above the center ; living chamber from 

 one-fourth to three-fourths of a whorl 

 in length ; aperture with deep ventral 

 sinus. Type D. costellatus. 



ammonia, Hall, 1879, Pal. N. Y., vol. 5, 

 pt. 2, p. 425, Up. Held. Gr. 



disciformis, Meek & Worth en, 1865, Proc. 

 Acad. Nat. Sci. Phil., p. 261, and Geo. 

 Sur. 111., vol. 5, p. 522, Keokuk Gr. 



hartti, Dawson, 1868, (Gyroceras hartti,) 

 Acadian Geol., p. 311, Subcarbonifer- 

 ous. Made the type of Hyatt's genus, 

 Stroboceras. 



highlandensis, Worthen, 1875, Geo. Sur. 

 111., vol. 6, p. 531, Coal Meas. 



inopinatus, Hall, 1879, Pal. N. Y., vol. 5, 

 pt. 2, p. 426, Up. Held. Gr. 



FIG. 733. Discites marcellensis. 



marcellensis, Vanuxem, 1842, (Goniatites 

 marcellensis,) Geo. Sur. 3d Dist. N. Y., 

 p. 146, Marcellus Shale. The type of 

 Hyatt's genus Centroceras. 



ornatus, syn. for D. marcellensis. 



toddanus, Gurley, 1883, New Carb. Foss., 

 p. 7. Publication invalid. 



tuberculatus, Owen, 1852, Geo. Sur. Wis., 



Iowa, and Minn., p. 581, Subcarb. 

 DISCOSORUS, Hall, 1852, Pal. N. Y., vol 2, p. 

 99. [Ety. diskos, quoit ; soros, heap or 

 pile.] Composed of a series of disks, 

 gradually diminishing in size from the 

 body chamber; outer edes rounded; 

 joining surfaces flat. Type D. con- 

 oideus. 



conoideus, Hall, 1852, Pal. N. Y., vol. 2, 



p. 99, Clinton and Niagara Gr. 

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

 58. [Ety. endos, within ; kera-s, horn.] 

 An elongated conical shell, resembling 

 an Orthoceras, and possessed of one or 

 more smooth siphuncles, which do not 

 expand in passing through the cham- 

 bers. Type E. annulatum. 



angusticameratum, Hall, 1847, Pal. N. Y., 

 vol. 1, p. 218. Trenton Gr. 



annulatum, Hall, 1847, Pal. N. Y., vol. 1, 

 p. 207, Trenton Gr. 



approximatum, Hall, 1847, Pal. N. Y., vol. 

 1, p. 219, Trenton Gr. 



arctiventrum, Hall, 1847. Pal. N. Y., vol. 

 1, p. 217, Trenton Gr. 



atlanticum, Barrande, 1870, Syst. Sil. de 

 Boh., vol. 2. p. viii, pi. 430, Quebec Gr. 



bristolense, S. A. Miller, 1882, Jour. Cin. Soc. 

 Nat. Hist., vol. 5, p. 85, Hud. Riv. Gr. 



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

 220, Trenton Gr. 



duplicatum, Hall, 1847, Pal. N. Y., vol. 1, 

 p. 219, Trenton Gr. 



egani, S. A. Miller, 1882, Jour. Cin. Soc. 

 Nat. Hist., vol. 5, p. 84, Hud. Riv. Gr. 



FIG. 734. Eudoceras longissimum. 



gemelliparum, Hall, 1847, Pal. N. Y., vol. 



1, p. 60, Black Riv. Gr. 

 insequabile, S. A. Miller, 1882, Jour. Cin. 



Soc. Nat. Hist., vol. 5, p. 86, Hud. 



Riv. Gr. 



