ON THE GREENLAND RIGHT- WHALE. 85 



as a distinguishing mark for the adult animal. The cavity of the mouth in the newborn 

 Greenland whale scarcely extends much farther backwards than in the rorquals (compare figs. 2 

 and 3 in our third plate). But as to the outward position of the glenoid articulations on 

 the lateral portions of the temporals, this characteristic, no less important for the Greenland 

 whale in opposition to the Cape whale, is prevalent in all stages of its development, as may 

 be seen by a reference to our illustration of the cranium of the newborn whale compared 

 with Cuvier's figure of the very small Cape whale. By this character, any cranium of a 

 Greenland whale, be it young or old, may always with certainty be distinguished from that of the 

 southern species. 



The glenoid articulations of the temporals are also, in another respect, conspicuously 

 characteristic of the Greenland whale, as compared with the Cape whale, for they are placed in a 

 position almost perfectly horizontal (see Plate II, figs. 1 and 2 and Plate V, fig. 1), whereas 

 in the Cape whale they are directed more forwards. This distinguishing mark derived from 

 the direction of the glenoid articulations, may also be applied in all periods of the animal's 

 life. 



As to the articulation between the cranium and the lower jaw in the Greenland whale, 

 it still remains for us to impart to our readers a most unexpected discovery, which we have 

 had the opportunity of making in our two small specimens preserved in brine (the newborn 

 one and the foetus). According to John Hunter's statement,' no synovial capsules are to be 

 found in the Cetaceans in this articulation, but only a dense mass of fibrous tissue, con- 

 taining in its interstices a viscid oil. This statement has either been expressly corroborated by 

 all succeeding observers, or, at all events, not contradicted. Nevertheless, we have found that 

 in the Greenland whale shortly before and after its birth, between the articular cavities of the 

 temporals and the condyles of the lower jaw, there is really a double synovial capsule of the 

 same breadth as the corresponding articular surface, and that both the capsules are entirely 

 without any communication with each other, in which particular they are therefore quite similar 

 to those of the mammalia in general, except only that we have not been able to find any 

 cartilaginous plate in the septum between them. We cannot help supposing that the synovial 

 capsules discovered in these whales, shortly before and after birth, must also be found in older 

 individuals of the species. How far they may also be discovered in the other right -whales, or 

 perhaps in many other Cetaceans, must be the object of future researches. 



To finish the examination of the peculiarities prevalent in the structure of the cranium of 

 the Greenland whale, by which the cavity of the mouth is enlarged in a manner so characteristic, 

 there still remains the form of the lower jaw. In conformity with the outward position of 

 the glenoid cavities with which it is articulated, the lower jaw is of course also extremely 

 broad behind, almost as broad as the whole base of the head, which is perhaps only very 

 little narrower than the broadest part of the body. The two rami have, accordingly, their 

 posterior extremities very much removed from each other, and, therefore, they are only very 

 slightly curved from each other at the middle of the head, whereas in their foremost part they 

 are strongly bent inwards to meet each other at the symphysis. In the Cape whale, it will be 

 seen by Cuvier's figures (1. c, fig. 6), that the lower jaw has rather a different form. In oppo- 

 sition to that of the Greenland whale, it is on the whole not so broad by far as the back part of 



^ 'Philosoph. Transact.,' vol. 77, page 384 (1787). 



