484 
and the lines are almost straight on the sides. The lines of growth 
alone are visible. ‘There are no prominent bands marking perma- 
nent apertures, nor are the characteristic coste of Trocholites 
visible, nor any longitudinal ridges in my specimens. Growth 
lines show that in the nepionic stage not only the form and sutures 
were distinct but also the aperture. The apertures are trumpet- 
like in the ephebic stage and have a moderate hyponomic sinus 
with broad lateral crests, increasing in prominence towards the 
dorsum. Whether there are sinuses in the contact furrow has not 
been determined, but one infers their presence*because the lines of 
growth incline apically just before reaching the lines of involution. 
The form of the whorl continues rounded in all species of this 
genus, although in some there is a distinct tendency towards angu- 
lation of the sides. 
The contact furrow appears very early in consequence of the 
close coiling of the whorl. This zone is not deep, but it is well 
marked and may extend nearly to the abdominal angles in some 
species and it remains throughout life. So faras known no specimen 
has been found with even a part of the last whorl free. The form 
of the whorl in section is consequently nephritic, except in some 
species having flatter sides and more pronounced abdominal angles 
than usual. 
In one species only, 7. cercudaris, is there any tendency to forma 
pentagonal whorl and this was not only very obscure but observed 
only in one specimen, the type form. The whorl is therefore very 
primitive. 
The length of the living chamber is given as usually about three- 
quarters of a volution by Schréder, but some of his species have it 
less than one-half of a volution. 7. Remelefand 7. ammonius have 
one invariably somewhat less than one-half of a volution in length. 
It is obvious that in this genus it varies between these limits. 
TROCHOLITES INTERNASTRIATA. 
LITUITES INTERNASTRIATA Whitf. Fort Cassin Foss. (Bul/. Am. 
Mus., New York, i, No. 8, Pl. xxix, Figs. 5-8). Fort Cassin: 
This species, of which I have studied the originals, has young of 
cyrtoceran form, with a good-sized umbilical perforation, as in 
Schroederoceras and Litoceras. The siphuncle is centren in 
what is probably the second septum, and it has not the prolonga- 
tion beyond this septum, as figured by Whitfield. It inclines 
