ON THE GREENLAND RIGHT-WHALE. 99 



process (c) on tlie upper mai'gin of the bone is, at the same time, shorter, so that the temporal 

 muscles are far more disadvantageously placed for lifting up the jaw than in the rorquals. 

 But besides this, it must be observed that this coronoid process (c) is extremely small in the 

 Greenland whale, an evidence of the feeble action of the temporal muscle, whereas in the 

 humpback it has the form of a broad and powerful prominence, and in the fin-whales is 

 developed into a highly projecting crest. 



The great opening for the vessels and nerves entering the lower jaw also shows some very 

 striking peculiarities in the Greenland whale, when compared with that of the rorquals. It is 

 situated, as usual, on the inner siu'face of the bone, close to the upper margin ; but its form is 

 almost circular, whereas in the rorquals it appears rather like an oblong fissure, and, what is 

 most characteristic, it is prolonged downwards into a narrow groove or cleft (Plate V, fig. 2, æ, w, æ), 

 which turns forwards near the inferior margin and runs along it, not to disappear until about the 

 anterior fourth of the bone. Although this groove is only to be considered as a vestige of the 

 cavity in which the primordial lower jaw (Meckel's cartilage) was situated during the embryonic 

 state,*it is preserved in the Greenland whale at least until the full-grown age, whereas in the rorquals 

 it has disappeared without leaving any traces even in very young individuals. 



In the inferior maxillaries of the Cape whale there is the same twisting of the surfaces 

 in front, the same want of any contraction behind that may deserve the name of a neck, the 

 same large opening for the vessels and nerves entering the lower jaw, as well as the fissure or 

 groove for Meckel's cartilage issuing therefrom ; but from those of the Greenland whale they may 

 be distinguished, partly by the bending of their posterior end mentioned above, partly by their 

 greater height as compared with their length, and, generally speaking, by their less slender 

 form. Judging from a very young individual of the group of the South whales (from the Bay of 

 Biscay), we might find an excellent distinguishing mark in the inner surface being almost as 

 convex from above downwards as the outer surface, whereas in the Greenland whale it is quite 

 flat in this direction. But, in reference to this point especially, we regret that we have 

 not had before us the skeleton of a Cape whale for direct comparison while making our 

 researches. 



To the bony frame of the hind part of the head may still be referred the two stylo-hyal 

 bones ; with these follows, naturally, the os hyoides itself, and with this, again, the larynx and 

 the trachea. This, therefore, may be the proper place for a description of these parts, and 

 we feel ourselves the more called upon to give it, as we have not only examined them in 

 our very young individuals, but also in the two full-grown ones of which the skeletons 

 were at our disposal. 



The hyoid is in the Greenland whale, as in all other Cetaceans, composed of three bones — the 

 OS hyoides properly so-called (see Plate VI, fig. 1, a), and the two stylo-hyal bones [b) ; these are 

 attached at their inner ends by means of a ligament (c) to a pair of wart-like processes (the 

 anterior hyoid cornua) on the anterior margin of the middle piece of the hyoid, externally by 

 means of a similar ligament {d) to the petrous bone. In the hyoid, properly so called, we must 

 distinguish between the middle piece and the two lateral cornua, all of which have special 

 points of ossification in the originally undivided cartilage. The middle piece of the hyoid passes 

 imperceptibly at the sides into the two lateral cornua ; on its anterior margin are the two anterior 

 hyoid cornua, as they are called, separated from each other by a deep notch in the mesial line ; 

 its posterior margin is evenly concave. 



