296 ALLEN: NEW ENGLAND WHALEBONE WHALES. 



left, passing forwards on the under surface of the penis." The vestigial femur has a small 

 muscle, the retractor femoris, ensheathed in ligament, and originating from the great interpelvic 

 ligament. It runs to the head of the femur, serving to pull it backward and a little inward. 

 Struthers states that he could not find the corresponding muscle in the Finback; he further 

 points out that its action is opposed by ligamentous connections. There would seem to be 

 little obvious cause for the retention of the femur and its connections. 



Skeleton. 



(For a detailed account of the skeleton see Struthers, 1889.) 



The skull differs in many details from that of the Finbacks. Compared with that of the 

 Common Finback Whale the more striking points may be briefly stated as follows. It has a 

 proportionately shorter and broader rostrum, whose outline passes basally by a sweeping curve 

 into that of the sides. The intermaxillaries expand slightly towards the tips, instead of tapering 

 evenly. The general profile of the skull is somewhat more curved than in the latter. The 

 shape of the nasals is rather characteristic: the two are produced upward to a sharp median 

 point, but their free edges are scarcely notched. There is also a slight median projection of 

 the frontals that separates the two nasals. The temporal opening is broader, and the frontals 

 are much narrowed laterally instead of being nearly square, owing to the backward trend of 

 the anterior border of the orbital plate. They thus approach the condition seen in the Right 

 Whale, where these bones are greatly narrowed. The huge supraoccipital, forming most of 

 the roof and back of the brain case, is narrower instead of broader than the condyles, at its vertex, 

 and has a very faint median ridge, or none, instead of a well developed crest. Its sides converge 

 regularly to the summit where it is broadly truncate; but in the Finback they become nearly 

 parallel for the dorsal third. In ventral aspect the palatals are relatively shorter and more 

 rounded at the ends. The coronoid process of the lower jaw is also less developed. 



In the following table (p. 297) are given the cranial measurements of a Humpback skull 

 (probably from Cape Cod) in the Museum of Comparative Zoology. 



The vertebral formula may be taken as C 7, D 14, L (10) or 11, Ca 21 == (52) 53, 

 according to True, who includes three New England specimens in his reckoning. All agree 

 as to the number of cervical and of rib-bearing vertebrae, but two have ten and one has 

 eleven lumbars, while the caudals vary from 19 to probably more. The loss of the minute 

 terminal bones of the spine often causes some uncertainty as to the exact number of caudals, 

 but Rudolphi records 22, other writers 21 in specimens examined. The latter probably repre- 

 sents the normal number. 



The cervical vertebrae are all free normally, and differ remarkably from those of the Fin 

 Whales in the reduction of the processes that form the vertebrarterial canal. In the second 



