ON THE ANATOMY OF THE NORTHERN BELUGA. 409 
In respect of its uniformly smooth surface, the spleen in Beluga differs 
from that of many cetacea, a distinctly lobulated character of that organ 
being noted by several observers in other species. In several, accessory 
spleniculi are found, but of these there is no trace in Beluga. These spleniculi, 
however, appear to be variable within the limits of even the same species. Dr 
JACKSON * describes them as being present in Globiocephalus, whilst Dr Murig,t 
on the other hand, as distinctly affirms their absence. The position of the spleen, 
lying as it does in relation to the superior aspect of the first gastric compart- 
ment, appears to be constant in all forms of the cetacea. 
Hyorp Bone. 
The hyoid bone is composed of the elements usually met with in the cetacea. 
The basi-hyal measures 2+ inches in length and the same in breadth between 
the thyro-hyals. Itis hexagonalinform. The posterior border affords attachment 
to the thyro-hyoid ligament, whilst the anterior articulates with the cerato-hyals. 
Of the two external borders of either side the anterior is occupied by the origin 
of the inter-hyoid muscle, whilst the posterior is continuous with the thyro-hyals. 
The lower surface is slightly convex, and presents a well-marked transverse 
ridge, to which a number of muscles, elsewhere described, are attached, whilst 
the upper surface is slightly concave. 
Thyro-hyals.—Each measures 24 inches in length and 1 inch in breadth 
at the base. Its free extremity is completed by a little cap of cartilage, and a 
plate of the same substance is interposed between the base of the thyro-hyal and 
the basi-hyal. 
Cerato-hyals are entirely cartilagmous, and measure 14 inch in length. 
Each is attached by one extremity through the medium of a capsular ligament 
to the free end of the stylo-hyal, whilst the other end lies in contact with a loose 
cartilaginous segment measuring half an inch in thickness, which separates it 
from the basi-hyal. The cerato-hyal is attached to the segment referred to by 
means of a fibrous capsule. 
Stylo-hyals, measuring 4 inches in length and 1 inch in breadth, are some- 
what flattened. Each is strongly curved towards the middle line, and is carti- 
liginous in its lower half. 
Muscies oF ToNGUE AND Hyorp Bone. 
By the time the subject came into our possession these muscles had to some 
extent been destroyed, partly by injury and partly by decomposition. We are, 
therefore, unable to give so satisfactory a description of them as we could desire. 
At the same time, we may be permitted to state that such observations as are 
here recorded are accurate so far as they go. 
7 IN. p: 163. + IL. See plate xxxiii. fig. 35. 
VOL. XXIX. PART I. DN 
