ANATOMY OF BALDEN OPTEEA EOSTEATA. 
257 
It is unnecessary to enter into any description of the globe of the eye, as it presented 
no points of departure from the frequently described normal cetacean type, in the 
great posterior thickness of the sclerotic, the comparatively small depth of the vitreous 
cavity, and the globular shape of the lens. 
Conclusion. 
The JBalcenoptera rostrata has already furnished a subject for several descriptions, each 
of them more or less complete. Of its osteology a most comprehensive and accurate 
account has been given by Mr. Flower in the Proceedings of the Zoological Society of 
London, 1864, with which, in most points, the osteological relations of the present speci- 
men will be seen to agree, the main points of difference being that in our specimen the 
foramina between the lateral processes of the axis were not completed by bone, but 
remained as large oval-shaped notches with an interval of a little more than 1 inch be- 
tween the free extremities of these processes. 
Another difference in the present specimen was the existence of a small osseous tubercle 
on the left side of the centrum of the seventh cervical vertebra, the rudiment of a para- 
pophysis. Mr. Flower notices the existence of a similar tubercle on both sides of the 
body of the same segment in a specimen in the Louvain Museum, but in the specimens 
described both by him and other authors this tubercle does not appear to have been 
present. Lilljeborg describes it as being developed in one individual more distinctly on 
the right side than on the left. 
There was also a discrepancy in the number of vertebrse, which in our specimen 
amounted only to forty-six, whereas in most of the other recorded instances from forty- 
eight to fifty are stated as the number present*. It is, however, possible, as our 
animal was immature, that two or more cartilaginous terminal bodies might have been 
present, and from their rudimental state have escaped detection. The last caudal bony 
centrum measured three-quarters of an inch in its transverse, and five-eighths in its per- 
pendicular diameter ; in texture it was spongy and friable. 
All the cervical vertebrse, as in the specimen described by Hunter, were free; 
whereas in the individual described by Dr. Gray in the “ Zoology” of the ‘ Erebus’ and 
‘ Terror,’ and also in one of the specimens in the Louvain Museum, the second and 
third were united by bone. 
The shape of the sternum of the present specimen differed from those heretofore 
described ; it had not the elongated cruciform outline of that described and figured by 
Mr. Flower, but, as before stated in this communication, it was somewhat heart-shaped ; 
this difference, however, might possibly be due to the immaturity of the animal. 
* A specimen from Bergen is described in the Scandinavisk Eanna, in which forty-seven vertebrse were stated 
to be the number present. This, however, Mr. Flower explains by the loss of the last one or two segments. 
9 
o 
MDCCCLXVIII. 
