CARBONIFEROUS CEPHALOPODS. 345 



those species of the same genus having more contracted abdomens, like mos- 

 quensis (sp. Tzwetaev), planotergatum as figured by De Koninck, and High- 

 landense (sp. M. and W). 



The last whorl was considerably altered by compression on one side, and 

 the drawings of the section and front view (Figs. 46, 47) are in a measure 

 restorations. 



ASYMPTOCERAS. 



The Cryptoceras Springeri, White and St. John,* is the type of Meek's 

 genus Solenocheilus described in the Invertebrate Paleontology, f and we 

 quote from this volume the following: "The group for which Prof. Worthen 

 and the writer [Meek] used the name Solenocheilus is almost entirely the same 

 for which d'Orbigny proposed the name Cryptoceras in 1850; but d'Orbigny's 

 name can not stand, because Barrande had used it for a genus of Cephalo- 

 poda in 1846. It is true that Barrande subsequently changed the name of 

 his genus to Ascoceras, because Latreille had in 1804 used Cryptoceras for a 

 genus of insects. If this was a sufficient reason, however, for changing Bar- 

 rande's name, Latreille's Cryptoceras would be equally in the way of d'Or- 

 bigny's Cryptoceras; and if not, then Dr. Barrande's genus would have to 

 retain his original name, which would render d'Orbigny's name equally un- 

 tenable."! 



*Trans. Chic. Acad.. I, p. 124. 



fU, S. Geol. Sur. Terr., IX, p. 491. 



+.The genus Cryptoceras was first described by d'Orbigny in his Prod. Stratigraphique 

 (Vol. I, p. 114), Naut. dorsalis, Phill. (G-eol. Yorks., Vol. II, PI. 17, Fig. 17, PJ. 18, Fig. 1-2) 

 having been cited as the type. The name of the genus had, however, already been quoted 

 on page 58 of the same volume, and Naut. subtuberculatus, Sandb., mentioned below as a 

 member of the genus. This species would, therefore, according to a very strict interpreta- 

 tion of the laws of priority, have to be considered the type. D'Orbigny, however, evidently 

 meant his description on page 114, and the species there mentioned should be accepted, and 

 considered the first mention on page 58 as a quotation. 



I followed the first course in my Genera of Fossil Cephalopods (Proc. Bost. Soc. Nat. His., 

 XXII, 1883, p. 283, and note, p. 297), reducing Cryptoceras consequently to a synonym of 

 Temnocheilus. I brought together under this name, having Tern, coronatus, McCoy (Syn. 

 Carb. Foss. Ireland, PI. 4, Fig. 15) as the type, all the Nautiloids having ventral and dorsal 

 lobes in their sutures, the siphon close to the venter, tuberculated shells, etc. There were, 

 however, in reality, two groups of species included under this name in the essay alluded to, 

 Asymptoceras in part and Temnocheilus as a whole. Temnocheilus should be limited to 

 those species having discoidal whorls and open umbilici, in which the increase of the whorl 

 by growth was slow along the abdomino-dorsal diameter and much more rapid along the 

 lateral or transverse diameter, especially near the angular junction of the sides and abdomen, 

 the venter being consequently much broader than the dorsum, and the sides necessarily 

 divergent, the umbilici deep. These also have large blunt tubercles along the angular junc- 



