44 KANSAS ACADEMY OF SCIENCE. 



the name ' Cryptoceras ' in 1850; bat d'Orbigny's name cannot stand, because Bar- 

 rande had used it for a genus of cephalopoda 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 suflBcient reason, how- 

 ever, for changing Barrande's name, Latreille's Cryptoceras would be equally in the 

 way of d'Orbigny's Cryptoceras; and if not, then Doctor Barrande's genus would 

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

 tenable.'"* 



In the Genera of Caphalopods I used the name of Ryckholt's Asymptoceras [see 

 Notice sur le Asympt. et Vestin, 1852,] for this same group, of which the type was 

 Naut. cyclostomus Phill. If Meek's reasoning holds good, it seems to us that both 

 the names Cryptoceras and Solenocheilus should be dropped in favor of Asympto- 

 ceras. The whorls increase very rapidly in all their diameters, and the living 

 chambers are correlatively short. The sides and venter are usually gibbous; the 

 dorsum has either no impressed zone or only a very narrow zone of depression, 

 showing how recent was the derivation of this group from the parent gyroceran 

 forms. The siphon is so near the venter that it interrupts the suture in most 

 species. So far as I have been able to see, however, it is to be noted that the edges 

 of the suture do not bend backwards to form a siphonal lobe similar to that of an 

 ammonoid. The siphon may become central in some adults, as in Asympt. crassi- 

 venter. The elliptical form of the young whorl, the large umbilical perforation, the 

 simple, fine, smooth longitudinal ridges of the whorl in the young, and the presence 

 of abrupt umbilical shoulders, indicate derivation from the opeu-whoried form, Aipo- 

 ceras. The sutures have broad ventral, lateral and dorsal inflections or lobes, and 

 small annular lobes. 



The European species, so far as now known to me, are Asymi^t. dorsale, sp. Phill., 

 crassiventer, sp. De Kon., normale, sp. De Kon., latiseptatum , sp. De Kon., cyclostomum, 

 sp. Phill., and all of them are from the carboniferous. Asympt. Springeri, sp. White 

 and St. John, capax, sp. Meek and Worthen, and the following, are all that are 

 known to me in this country, all three being also carboniferous, coal measures. 



*NoTE.— The genus Cryptoceras was first described by crOrbigny in his "Prod. Stratigraphiqiie," 

 (vol. I, p. 114,) Naut. dorsalis Phill. (Geol. Yorks., vol. II, pi. 17, fig. 17, pi. 18, figs. 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. subtuberculatvs Sandb. mentioned below as a member of the genus. This species 

 would, therefore, according to a very strict interpretation of the laws of priority, have to be consid- 

 ered 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. Hist., XXII, 

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

 brought together under this name, having Tein. 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. Temno- 

 cheilus should be limited to those species having discoidal whorls and open umbilici, in which the in- 

 crease 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 abdo- 

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

 gent, the umbilici deep. These also have large, blunt tubercles along the angular junctions of the 

 sides and abdomen, and the sutures have broad ventral, lateral and dorsal lobes. The Devonian forms 

 of Temnocheilus, so far as known, have no annular lobe in the center of the dorsal suture; but this is 

 present in some carboniferous species, like r<m. latus De Kon. (Calc. Carb., pi. 24, fig. 2). The siphon, 

 also, Is near the venter In Devonian forms, but shifts nearer to the center in some carboniferous spe- 

 cies, like Tern, latus. This organ, however, does not approach the periphery near enough to Interrupt 

 the line of suture on the venter in any species. 



