345
those species of the same genus having more contracted abdomens, like mosquensis (sp. Tzwetaev), planotergatum as figured by De Koninck, and Highlandense (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, 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 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 sufficient reason, however, for changing Barrande's name, Latreille's Cryptoceras would be equally in the way of d' Orbigny'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 untenable."
"Trans. Chic. Acad., I, p. 124.
U. 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. (Geol. Yorks., Vol. II, Pl. 17, Fig. 17, Pl. 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 interpretation 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 ofTemnocheilus. I brought together under this name, having Tem. coronatus, McCoy (Syn. Carb. Foss. Ireland, Pl. 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 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 centre of the dorsal suture, but this is present in some Carboniferous species like Tem. latus, DeKon. (Calc. Carb., Pl. 24, Fig. 2). The siphon, also, is near the venter in Devonian forms, but shifts nearer to the centre in some Carboniferous species, like Tem. latus. This organ, however, does not approach the periphery near enough to interrupt the line of suture on the venter in any species.