XArTiLiD.1:. 
167 
chamber of this species and of Asymp. {Xaut.') conspicuum^ ibid, 
pi. 19, does not enable ns to separate these species.” 
RemarJcs. The name Solenocheilus of !M!eek and ^orthen replaces 
.hat of Cryptoceras proposed by d’Orbigny in 1849. The latter was 
preoccupied by Barrande for a genus of Cephalopoda in 1846, though 
it was afterwards changed by that author to Ascocei'as, because 
Latreille had employed the name Cryptocerus for a genus of insects 
in 1804. However, as Heek ^ observes, the same reason for changing 
Barrande’s name would have equal force in reference to d’Orbigny's, 
both being anticipated by Latreille’s. Beferring to American species 
of Solenocheilus, Messrs. Meek and Worthen offer the following 
remarks : — “ In this country we already know several Carboniferous 
species that agree with d’Orbigny’s t}"pe in the character or position 
of the siphuncle, and we find in all of these another remarkable 
peculiarity of the lip on each side. That is, it is drawn [out] so as 
to form a kind of little canal, or spout-like channel, much as we 
see in Arrjonauta gondola, Adams. A good example of one of these 
shells is figured and described by Dr. White and Prof. St. John, 
under the name Nautilus {Cryptoceras) Springeri, in vol. i. p. 124, 
of the Transactions of the Chicago Academy of Sciences for 1867"; 
and this may be regarded as the type of the group. It also includes 
our N. {Cryptoceras) Leidyi^, N. {Crypt.) capax^, and the species 
described below [AT. {Solenocheilus) collectus % M. & W.], with pos- 
sibly our A". {Crypt.) Rodcf or densis^. ...” 
The genus Asymptoceras, established by Byckholt at the same 
time (1852) as Vestinautilus, already referred to, was very justly 
rejected by de Koninck upon the same grounds as the latter, viz. 
that it was founded upon erroneous data. It appears that Byckholt 
mistook a calcareous concretion lodged in the body-chamber of a 
specimen of Nautilus cyclostomus, Phill., for one of the mandibles of 
the animal, and went on to describe the shell as differing from that 
of the Nautili proper by the separation of the last whorl from the 
preceding ones, and its projection in a nearly straight line, so that 
the mouth never touches the penultimate whorl. The test appeared 
to him to be papyraceous, as in the Argonauts ; the siphuncle 
dorsal, as in N. dorsalis, Phill. De Koninck states that the speci- 
^ United States Geol. Surv. Terr. 1876, vol. ix, p. 493. 
^ I have not had access to this work. 
® Proc. Acad. Nat. Sci. Philadelphia, 1865, p. 262. 
^ Ibid. 1865, p. 262. Also in Geol. Surv. of Illinois, 1875, vol. vi. p. 532, 
pi. xxxiii. ff. 1, la. 
^ Proc. Acad. Nat. Sci. Philadelphia 1870, p. 48. ® Ibid. 1866, p. 275. 
