BUCHICERATID 2. 
bo 
“| 
BUCHICERAS Hyatt. 
This genus was formerly described by myself as including several 
different species that have since been separated into distinct genera, by 
Douvillé, Grossouvre, and others, and by myself, in Zittel’s Text-book of 
Paleontology. The affinities of Buchiceras are not, in my opinion, very 
close to any of the forms formerly referred to Acanthoceras as supposed by 
some authorities. The sutures are quite distinct from those of any of the 
families of Mammitida on account of the extraordinary breadth of the second 
lateral saddles. The development is similar to that of some forms of Hys- 
tatoceratidee and Peroniceratide in that it is at first discoidal, compressed, 
and smooth, then keeled, becoming costated and tuberculated later, and 
the sutures approximate more closely to those of the young of these families 
perhaps than to others. Nevertheless the ontogeny differs in that Buch- 
iceras does not subsequently acquire prominent costz, and the keel tends to 
disappear instead of becoming larger with increase in size of the volutions. 
The nodes, on the other hand, increase in size and prominence, especially the 
inner row on the umbilical shoulders. The faint serrations on the keel and 
other ornamentation suggest affinities with Barroisiceras, but the sutures and 
the absence of a third line of lateral tubercles, which appear in some forms 
of Barroisiceras, are not favorable to this solution of the affinities. The 
same objections apply almost equally to keeled forms of the Prionotropidee 
in which the young resemble more or less closely those of B. bilobatum. 
The dorsal sutures are very remarkable and perhaps may eventually assist 
in placing this genus in closer connection with others. The primitive first 
lateral saddle is retained in Buchiceras until a late stage, and perhaps 
throughout life; it is undivided, except by small entire marginal lobes, but 
it is distinetly bifid. 
BucHICERAS BILOBATUM Hyatt. 
Pl. I, figs. 4-9. 
Buchiceras bilobatum Hyatt, 1875, Proc. Boston Soc. Nat. Hist., Vol. XVII, p. 370. 
Buchiceras bilobatum Douvillé, 1890, Bull. Soc. géol. France, 3d ser., Vol. XVIII, 
p- 284. 
The young, for the first two, and perhaps part of the third volution, 
must have had smooth sides and was obviously very discoidal, flat, and 
keelless. The aspect of this species must have been very similar to Mojsi- 
sovicsia. The keel comes in upon an elevated venter previous to reaching 
