532 
The sutures have ventral and dorsal lobes and lateral lobes in the 
ephebic stage, but in the earlier stage there are ventral saddles. 
NEPHRITICERAS LIRATUM. 
NAUTILUS EIRATUS, sp. Hall (Pad. WV. Y.,'v. Pt. 1, Pl. lviipanncieee 
Ibo)f 
This species in the metanepionic substage is distinctly annulated 
and also has broad longitudinal ridges, as shown in Hall’s figures 
on Pl. lx. These ridges disappear together with the annulations on 
the abdomen of the paranepionic volution, but persist longer on the 
dorsum, and in some specimens they are very large flutes on the 
sides even in the neanic, as is shown in Hall’s Fig. 3, Pl. Ivii. 
In the neanic stage the form of the volution changes from sub- 
trigonal to a broad depressed oval. 
No impressed zone has been observed, but this may be due to the 
age of the shells so far observed, none of which as figured, nor so far 
as I have seen, exceeded one volution. 
NEPHRITICERAS JUVENIS. 
NAUTILUS LIRATUS, var. JUVENIS, Hall (Pad. WV. Y., v, Pt. ii, Pl. lvi, 
Figs. 5, 6). 
This shell, described as a variety of “vatus by Hall, is obviously 
distinct. The form changes more rapidly than in “raf¢us and, in 
the fragment of the nepionic volution figured by Hall, it may also 
be seen that the longitudinal ridges are much smaller than in /ra- 
tus, more like those of the young of Wephriticeras buctnum. It dif- 
fers from the last in having no impressed zone at the same age. 
It is highly probable than an impressed zone appeared in a later 
stage than has yet been described. 
NEPHRITICERAS SUBLIRATUM. 
NAUTILUS SUBLIRATUM, sp. Hall (Padé. iV. Y., v, Pt. ii, Pl. lvii). 
This species has similar changes of form to those of /iratwm, but 
it is altogether a broader whorled species and acquires the nephritic 
outline at an earlier stage of growth, and probably has in perfect 
specimens a smaller umbilical perforation. 
There are no longitudinal ridges on the ventral side in the orig- 
inal specimen, which was in the neanic stage of development, but 
these are large and persistent on the dorsum as in Wephriticeras 
firatum. In Hall’s figures the sutures have been confused with the 
