XAUTILID^. 
103 
rounded elevation, extending from the tongue-shaped sinus of the 
outer margin to the opposite point of the inner margin, nearly in 
the middle of which elevation is the very large siphuncle . . . 
Remarhs. This species has been held by de Koninck and M^Coy 
to be identical with E. hilohatum, J. Sow. ; but a careful comparison 
of the two species will, I think, convince any one that there are 
differences between them quite sufficient to warrant their separa- 
tion. Unfortunately J. Sowerby gave but one figure of the type 
specimen, and that a little foreshortened, therefore its characters 
were not all displayed. On comparing the type of E. bilohaium 
with a specimen of E. ditellarium, it is at once apparent that the 
latter is a much broader and more rapidly expanding shell than 
the former. The whorls also in E. diteUarium are considerably 
higher in proportion to their width than those of E. hilohatum. 
These differences appear fully to justify the retention of the two 
names. 
Authorities differ as to the identity of de Verneuil’s X. ditdlarius 
with the present species ; M‘Coy thinks they are the same ; while 
de Koninck regards the ditdlarius of de Yerneuil as a distinct 
species, stating that its umbilicus is larger than that of the hiJohatus 
of Sowerby, and also that its general form is less globular than the 
latter. 
The Nautilus ferratus of Cox resembles hilohatus so very closely 
that the former can be scarcely more than a variety of the latter ; 
the American form occurs also at the same horizon as the English 
one ; and under similar mineral conditions, both being associated 
with iron in the beds in which they are found. 
Horizon. Coal-Measures. 
Localities. Madeley, Coalbrookdale, Shropshire ; Hartley, Wor- 
cestershire. 
Well represented in the Collection. 
Ephippioceras costatum, Eoord. 
Char. This species is distinguished from E. ditellarium (to 
which it is, however, very closely related) by the character of the 
septa and by the surface ornaments. The septa in E. costatum do 
not form such an acute lobe upon the periphery as do those of 
E. diteUarium, and they are also a little wider apart in the former 
species than they are in the latter. Moreover, E. costatum is pro- 
vided with prominent transverse costse which are strongest upon 
the sides of the shell, where they swell out into heavy folds. These 
