435 
lines of growth, which are more or less sporadic in shells of this 
group. ‘These primitive coste are probably due to the imperfect 
resorption of the more or less expanded borders of the apertures 
occurring in some shells but not in others during the progressive 
stages of development but common in all shells in the gerontic 
stage. 
The shell is very thick on the venter, somewhat thinner, but still 
thick on the sides and dorsum. 
The type is Zarphyceras prematurum. 
The species of this genus are as follows: * 
Larphyceras Aucoint, Hyatt, Newfoundland. 
Ke prematurum, Hyatt, Newfoundland. 
frarnsworthi (sp. Billings, fars.), Phillipsburg. 
ce 
“ Champlainense, sp. Whitfield, Fort Cassin. 
if Seeleyt, sp. Whitfield, Fort Cassin. 
a extensum, Hyatt, Newfoundland. 
Mac Donaldi, n. s., near Lexington, Va. 
This last species has a form and suture like that of Champlain- 
ense, but the siphuncle is nearer the venter and the young have 
flatter and more divergent sides and broader abdomen in the neanic 
stage. 
TARPHYCERAS. AUCOINI, N. S. 
LLoe:; Port au Port, 
Pl. iv, Figs. 17-22. 
The ananepionic substage seen in the somewhat rough casts is 
given in Figs. 20-22, Pl. iv, from the side and front. These figures 
* Nautilus calciferous of Billings (Pal. Foss., i, p. 258) is probably a species of this genus 
surviving in the later forms of the Quebec at Port au Choix. The small siphuncle and 
its position appears to indicate this, but I have no specimens of this species and have 
not seen any at Ottawa. 
+ This species has two or more very distinct species. The one referred to above has an 
elliptical or oval whorl in the ephebic stage, the dorsum a little broader than the venter. 
There is a contact furrow in the neanic and ephebic stages. The sutures have ventral 
saddles, with probably slight dorsal lobes in the zone of involution, and a free living 
chamber over one-half of a volution in length. The siphuncle is subyentran in the 
ananeanic substage, becoming propioventran in the paraneanic and yentrocentren in 
the metephebic substage. The diameter of the largest specimen, somewhat compressed, 
was 140 mm. by 146 mm.; the estimated longest diameter of this through the free living 
chamber was about 160 mm. ; 
The type of Farnsworthi is a very distinct species and belongs to another genus and is 
cited below under the heading of Aphetoceras. 
