356 MR. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 
centres, but differs in its rugged massiveness, in its broad triangular shape, and espe- 
cially in the tardy union of its lateral parts across the middle line. 
Neither of the three skeletons of Cachalots in this country has any vestige of 
ossified sternal ribs. Wall says, “ the sternal parts of the ribs are all cartilaginous” *. 
We may therefore conclude that Physeter resembles its congeners Kogia, Micropteron, 
and Hyperoodon in this important character. 
Pectoral Limb. 
Besides the limb-bones belonging to the skeleton, from which unfortunately some of 
the phalanges were lost, Mr. Crowther has kindly placed at my disposal two pairs of 
complete fins of adult male Cachalots, with all the bones in their natural connexion. 
Nothing is therefore wanting in the materials for completing our knowledge of this 
portion of the skeleton. 
In relation to the entire size of the animal, the pectoral limb of the Cachalot is com- 
paratively small, the length of its osseous parts from the head of the humerus to the 
terminal phalanges being 4! 10", or about of the entire skeleton. The terminal 
portion is broad, and rounded or almost truncated at the extremity, the digits being 
spread apart, and all five well developed, especially the second, third, and fourth, which 
do not differ greatly in length. This form of hand is also found in the other Physeteride, 
the Platanistide, and Beluga and Monodon among the Delphinide. It has its greatest 
contrast in the narrow lanceolate fin, with adpressed digits, of which the second and 
third far exceed the others, characteristic of Delphinus, and which reaches its extreme 
development in Globiocephalus. 
An observation in Wall’s memoir has given rise to the idea, since repeated in other 
works, that there is a want of symmetry in the two pectoral limbs of the Cachalot, the 
bones of the right being described as “considerably larger than those of the left.” 
However this may be with the specimen in the Sydney Museum, there is certainly no 
appreciable difference either in size or form in the bones of the two pectoral limbs in 
any of the skeletons that I have examined. 
The scapula is higher in proportion to its breadth than in any other Cetacean ; 
indeed it is the only one known in which the height actually exceeds the greatest 
transverse breadth. The whole of the outer surface (corresponding to the infra- 
spinous fossa of the ordinary mammalian scapula) is remarkably concave, and the 
internal surface is in a corresponding degree convex}. The spine, as is usual in the 
Cetacea, has a very narrow base of origin, placed near the neck of the bone, and so 
close to the anterior edge as to reduce the supraspinous fossa to almost imperceptible 
* Op. cit. p. 28. t+ Op. cit. p. 5. 
+ In the Sydney skeleton, according to Wall’s figure, the internal surface of the scapula is placed outwards. 
The same is the case with the skeleton at Burton Constable, the articulator having doubtless been misled in 
both cases by the above-mentioned peculiarity. 
