﻿444 



slightly convex and slope evenly and divergently outwards and con- 

 sequently appear flattened in some specimens. 



The envelopment covers the abdomen, which last is prominently 

 convex. 



The length of the sub-V-shaped dorsal lobe in the sutures is 

 greater than in any species I have yet seen, and this is very instruc- 

 tive. Occurring as it does in a shell which is not very involute, 

 and with a contact furrow but little exceeding the ordinary 

 dimensions, it shows that the depth of the dorsal lobe in the 

 sutures is not only correlated with the extent and depth of the 

 contact furrow but also largely dependent upon the concavity of the 

 septa. In other words, if this species had had septa of ordinary 

 concavity the dorsal lobes in the sutures would not have been so 

 deep and sub-V-shaped as they are. The sutures have also broad 

 lateral lobes running well forward to sharp saddles at the lines of 

 involution. There are broad saddles at the abdominal angles and 

 shallow ventral lobes or straight sutures across the venter. The 

 siphuncle becomes intracentroventran in the ephebic stage and is 

 very large, as it is in Eurystomites Kelloggi. The whorls come in 

 contact in the ananeanic substage. The shell grows quite large, 

 but, so far as I have seen, none have any part of the last whorl free. 



Eurystomites Virginiana. 



Nautilus Kelloggi (?) {pars), Whitf. (not figured). 



Loc, near Lexington, Va., and Fort Cassin. 



This shell had more cylindrical whorls and more numerous and 

 straighter sutures at all stages than in Kelloggi. The siphuncle is 

 nearer the venter, and in the type-specimen, which is over 90 mm. 

 in diameter (in collection U. S. National Museum), it is still almost 

 subventran at the entrance into the living chamber. This last is 

 less than one-half of a volution in length. The whorl is almost 

 circular in this specimen at all stages observed, including the neanic 

 stage, and the involution is very slight: the dorsal lobe correlates 

 with this, being correspondingly shallow and narrow. The sutures 

 otherwise resemble those of Kelloggi, but are straighter, and the 

 three specimens from Virginia do not show the ventral lobes that 

 often occur in Kelloggi. 



There is a young specimen in the American Museum under the 

 name of Kelloggi, from Fort Cassin, that appears to belong to this 

 species, having similar sutures, form of whorl and involution. 



