ON THE OSTEOLOGY OF UlSSO's GRAMPUS, 
413 
ON THE OSTEOLOGY OF RISSO'S GRAMPUS. 
( Grampus Griseus.) 
BY F. H. BALKWILL. 
I have prepared, articulated, and added to the Museum the entire 
skeleton of the Risso's Grampus reported last year. The skeleton 
is, I believe, perfect, with the exception of the pelvic bones, 
which were very small, one tympanic bone, and four teeth, which 
have been reserved for examination. One tympanic bone is 
still attached to the skull for reference, and the place of 
the absent teeth is supplied by plaster models. Considering 
that this specimen is unusually interesting, I shall give it a full 
description. 
Skull : Length, 1 foot 6 inches ; Width, 1 foot. A symmetrical 
septum of nostrils being three-quarters of an inch 
to the left of central ridge of occiput. 
Lower jaw nearly as long as upper. Teeth, a \ 
Length, from an inch to an inch and a quarter. 
Width at base, about half an inch. Conical, curved, 
with a slightly oval section, very hollow, with 
enamelled crowns (a) for nearly half an inch, which 
were more curved than the general curve of the 
tooth ; points slightly worn. 
The backbone consists of sixty-one vertebrae, of which the 
following is a description : The seven cervical vertebrae are all 
anchylosed together at the top of the neural arch ; but the lateral 
processes are quite distinct, and the bodies, although very close, 
appear to be separated by articular cartilage. That an animal 
with so short a neck should still so distinctly show the mammalian 
typical number of cervical vertebrae is so interesting that a draw- 
ing is appended. 
