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 Hyjieroodon 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 

 comjDlete 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 -yy 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 Physeteridce, 

 the Platmiistidce, and Beluga and Monodon among the Belphinidce. 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 Belphinihs, and which reaches its extreme 

 development in GloMocephalus. 



An observation in Wall's memoirf 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 siu-face (corresponding to the infra- 

 spinous fossa of the ordinary mammalian scapula) is remarkably concave, and the 

 internal surface is in a corresponding degree convexj. 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. ek. p. 5. 



t 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. 



