The Skull of the Manatus Senegalensis and Manatee. 261 
sembling so closely, in that state, the larva of the common 
Cheimatohia brumata, as to be almost undistinguishable. 
IT. Remojrlcs on some Comparative Anatomical Distinctions between the 
Skull of the Manatus Senegalensis and that of a Manatee from the 
Bay of Honduras. Bj James M'Bain, M.D., R.N. (Specimens 
exhibited.) 
The skull of a Manatee from the Bay of Honduras, which 
I now exhibit to the Royal Physical Society, was presented 
to the Hunterian Museum of Glasgow about seventeen years 
ago, along with a considerable portion of the skeleton, by 
Mr James Banks, late of Belize, Honduras, but latterly re- 
siding at Prestonpans.* 
In the remarks which I shall have occasion to make on 
this skull, it will be necessary to refer to the " Notice of a 
Skull of a Manatee from Old Calabar," which I read at a 
meeting of the British Association at Aberdeen in Septem- 
ber 1859, and which was published in the Proceedings for 
that year. 
In the skull from Old Calabar, which I have brought here 
for comparison, the occipital bone, petro-mastoid, and tym- 
panic bulla, are wanting ; and in the skull from the Bay of 
Honduras there is a transverse section at the base of about 
an inch in breadth, extending across between the tympanic 
bones, which involves the loss of nearly the whole basi- 
occipital. It is in this lost part that several of the princi- 
pal foramina at the base of the skull are situated. 
That portion of the crista interna formed by the inner 
tables of the frontal bone, extending upwards and back- 
wards from the largely developed crista galli of the ethmoid 
in the skull from Old Calabar, is almost wanting in the 
skull from Honduras. The parietal part of the crista in- 
terna in the latter skull is well-marked, increasing in size 
backwards until it expands into a large internal occipital 
protuberance, with a broad transverse ridge which separates 
the cerebrum from the cerebellum. The palate of the skull 
from Honduras, measured from the incisive edge of the pre- 
maxillary bones to the posterior part of the spinous cleft of 
* I regret to see a notice of Mr Banks's death in the " North British Ad- 
vertiser," as having occurred at Prestonpans on the 6th instant. 
