107 
BELLEROPHON Montfort. 
Gen. Char. An involute, univalved shell; 
nearly spherical; the last whorl enclosing 
the others ; aperture arched, terminated by 
the extremities of the transverse columella, 
(or axis), and furnished with a sinus in the 
centre of its outer edge. 
In general form the shells of this genus resemble the 
Nautili, but they have no septa; the two sides, if they 
may be so called that are indicated by the extremities of 
the axis, are nearly similar, in which particular they are 
distinguished from Ovula, Bulla, and most other invo- 
lute Genera ; they are sometimes umbilicated ; the front 
edge of the aperture has a sinus in it, from which, in 
most species a band runs round the whorl, and forms a 
kind of keel ; as tliis keel is very variable in size, the 
presence of it is not considered as essential to the 
Genus, but will serve to divide it into two sections by ; 
the first without ; the second , with a central band. 
Had not M, Defrance ascertained from a specimen 
formerly belonging to De Montfort, that his Bellero- 
phon was not a chambered shell,* the Genus would 
probably have long remained without being recognized, 
although several species are far from being of rare oc- 
currence in the older Limestone rocks ; it is not unlikely 
that De Montfort was misled in his generic character, 
by imperfect specimens of Nautilus biangulatus,f t. 458. 
f. 2, which he might consider as portions of the same 
species, as it occurs in the same limestone. 
Ellipsolites ovatus, t. 37, belongs to this Genus. 
* Annales des Sciences Naturelles Vol. t. p. 264. 
Zoological Journal, No. 2. p. 223. 
1 1 have just received specimens of this from Ireland, several inches ia 
diameter, and also learnt that it was a mistake to give Bristol as th§ 
locality of the specimen figured, it also £ame from Ireland, 
