438 
bled closely Aucoinz, but the abdomen becomes more prominent 
and the contact furrow is deeper and broader in consequence of 
this and the breadth of the venter. 
The siphunele in the paranepionic substage issubventran, becom- 
ing propioventran in the ananeanic as seen in section above in 
Fig. 14, and extracentroventran in the septum seen below in Fig. 
12. The position alters slightly in the succeeding stages. 
The living chamber is obviously over one-half of a volution in 
length and is shown in an incomplete fragmentary condition in the 
outline on the farther side of Fig. 12; the form in section of the 
same specimen partly restored is given in Fig. 13, Pl.iv. The 
depth of the dorsal lobes in the sutures is shown upon the venter 
of the exposed whorl in the upper part of the section which is still 
covered by the dorsal layer and the remnants of the septa. 
‘TARPHYCERAS EXTENSUM. 
Loc., Port au Choix, Newfoundland. 
This fossil resembles Zarphyceras Seeleyz, but has a shorter living 
chamber and the living chamber and part of septate whorl are free 
in gerontie stage. The contact furrow increases in depth with the 
ephebic stage and then decreases with the approach of the gerontic 
stage. The ventro-dorsal diameter slightly decreases, as is shown 
in Fig. 1, Pl. vi, in the paragerontic substage, when the whorl is 
almost straightened out, and at the same time the impressed zone 
is found to be wholly lost, as shown in the section, Fig. 2. 
In section 4 the inner whorl represents a section of the 
ephebic stage and the outer whorl is the gerontic stage. The 
uppermost, with siphuncle nearer the venter and reduced impressed 
zone, is the anagerontic, and Fig. 2 is the paragerontic sub- 
stage. The whorls are apparently smooth. ‘The septa are not very 
concave. The sutures have ventral saddles, dorsal lobes and slight 
lateral lobes. In the anagerontic substage they are nearly straight 
on the sides and decidedly inclined forwards. 
TARPHYCERAS CHAMPLAINENSE. 
NauTILUS CHAMPLAINENSE, Whitfield, (Bull. Am. Mus., New 
York, Volaj7Pigst9.93, Pl, 32). 
Loc., Fort Cassin, Lake Champlain. 
Pl. iv, Figs. 4-11. 
The nepionic stage of this species, as in others of this group, has 
