ANATOMY OF MEGAPTERA LONGIMANA. 113 



front of the broad low odontoid, with rather a narrower ending 

 than the corresponding surface on the atlas. The furrow 

 between it and the right lateral articular surface resembles 

 very much the corresponding one on the atlas, in its breadth 

 and in the character of its surface ; that on the left side is very 

 shallow, ^ inch in breadth at the middle, widening upwards and 

 downwards, but well defined along its margins, and its surface 

 resembles that of the ligamentous area rather than bone that 

 had been covered by cartilage. 



The breadth of the entire odontoid and ligamentous area is 

 7 inches in Megaptera, 5i in the B. musculus. The breadth of 

 the entire upper surface of the body is ^ inch less in Megap- 

 tera (13j) than in the B. musculus. The less depth of the 

 lateral articular surfaces in Megaptera is marked. 



Transverse P7'0cesses of tlie Axis. — The axis of Megaptera 

 is easily distinguished from that of B. musculus by the trans- 

 verse processes. In B. musculus the upper and lower pro- 

 cesses unite to complete the ovoid ring and form a great 

 common terminal plate external to the ring. In this Megap- 

 tera the ends of the upper and lower processes are 3 inches 

 apart. The ends have been covered by cartilage.^ They 

 incline a little to each other, mainly by curvature of the upper 

 process. Were the ring to be completed by the up-growing of 

 the inferior process, the ring would have very nearly the same 

 diameters as in the B. musculus. 



But, even short as they are, the transverse processes of 

 Megaptera differ materially from those of B. musculus in form 

 and direction. The inferior process has the following dimen- 

 sions ; in B. musculus, at the narrowest part, height 3| inches, 

 thickness If ; in Megaptera the corresponding measurements 

 are 2 inches and 2i. The superior process, on the contrary, 

 in Megaptera exceeds that of B. musculus both in height and 

 in thickness. Viewed antero-posteriorly, the superior process in 

 B. musculus is only about half the breadth (height) of the 



^ The soft tissue completing the ring of the axis of a foetal Megaptera was found 

 by Eschricht (Zoc. cit.,j). 133) to be cartilaginous. In the 46-feet-long skeleton 

 of Megaptera in the Brussels Museum, noticed by Professor Flower {Proc. Zool. 

 Soc, 1864, p. 416) as " a nearly adult individual," the transverse processes of 

 the axis are noted as "short, thick and convergent, but still with a wide space 

 between them." 



