ANATOMY OF MEGAPTERA LONGIMAKA. 51 



The acetabular cartilage which I found in the Greenland 

 Bight- Whale (loc. cit, figured in Plate XIV.), and which I find 

 to be present in my 50-feet-long B. musculus, is entirely absent 

 in this Megaptera. On raising the periosteum carefully at the 

 promontory and from both surfaces near it, no cartilage of any 

 kind is seen. 



18. THE FEMUR 1 (figs. 15 and 16, F.). The femur is entirely 

 cartilaginous. On horizontal section in its whole length, the 

 cartilage is seen to be traversed by the usual large Haversian 

 canals, in that section divided transversely, at distances of ^ to J 

 inch, less towards the tapering anterior end, wider apart towards 

 the thicker posterior end. It is closely embraced by its peri- 

 chondrial capsule, averaging J inch in thickness, thinner behind 

 thicker in front. The difference in length between the right 

 (3| inches) and the left (5 J inches, the cartilage proper 5 inches) 

 is striking. The form is that of a pine-cone, a little flattened, 

 so that the surfaces are inferior and superior, the borders internal 

 and external. In Eschricht's figure of the foetal cartilage, it has 

 a somewhat pear-shape, with a pinched anterior third ; in 

 the adult he defines the form as " fast wie die einer mensch- 

 lichen Kniescheibe," but his figure of it is longer and less 

 pointed than a human patella. In this Megaptera (as seen in 

 fig. 16, R. and L.) it presents two slight lateral projections on 

 both borders with a constriction between. The projections are 

 seen to correspond to the attachment of ligaments or other 



1 The presence of this bone in Megaptera was discovered by Eschricht. 

 "Writing in 1840 (loc. cit., p. 136) he mentions having first found it in foetal 

 Humpbacks, male and female, as a cartilaginous nodule. In his figure (fig. 43) 

 of the full size in a 78-inch-long fcetus, it is somewhat under J inch in length, 

 the pelvic bone If inch. He figures it (fig. 44, reduced to |th, the natural 

 length would be nearly 2 inches) from a full-grown Humpback, the pelvis of 

 which had been sent to him from Greenland, adding the important fact that, in 

 this "erwachsenen Thiere," "Er war hier grosstentheils verknochert. " "When 

 the presence of a rudimentary femur in B. musculus was discovered by Professor 

 Flower, C.B. (Proc. Zool. Soc., 1865), it was in the condition of a cartilage, 1J 

 inch long by f inch broad, although the whale was 67-feet-long and a male. In 

 the 64-feet-long B. musculus (loc. cit., 1871, and plate vii. fig. 3) I found it 

 mostly in an ossified condition, 2 inches in length, ! in breadth, f in thick- 

 ness, ossified in the proximal f of its length. But in my 50-feet-long B. mus- 

 eulus, also a male, the femur is entirely cartilaginous, 1^ to If inch long by 1 inch 

 broad. A preliminary account of the dissection of the hind limb of this Megap- 

 tera was read by me at the meeting of the British Association for the Advancement 

 of Science, at Montreal, in August 1884. (American Naturalist, February 1885). 



