98 



ESCHRICHT AND REINHARDT 



Of peculiarities in the lower jaw of the adult Greenland whale, we shall first point ont that at 

 their anterior flattened end the rami are twisted in such a manner that their inner surface is 

 turned upwards and the outer surface downwards, so that at their junction they do not meet 

 each other so much by their points as by the most anterior part of their inferior margins (see 

 Plate V, fig. 2,/). This peculiar twisting of the anterior ends of the rami of the lower jaw 

 is not yet perceptible in very young individuals, and in the rorquals it can only, at the most, 

 be said to be indicated by a slight inflection. 



We shall find many other, and scarcely less conspicuous, characters in the posterior ends of 

 the branches of the lower jaw in the Greenland whale. 



As such, Ave have already mentioned the perfectly difi'erent position of the articular surfaces, 

 which may be pointed out even in the newborn animal, and also the surprising thickness of 

 this region as compared with the middle and foremost parts of the bones. To enter on a 

 somewhat more detailed examination of the peculiarities appearing here we must refer our readers 

 to Plate V, fig. 2, where the right branch of the lower jaw of the full-grown Greenland whale is 

 shown, seen from the inside ; and fig. 3, where the posterior part of the same is seen from 

 above. For a comparison we shall insert here a woodcut illustration of the hindmost parts of 

 he right lower jaw-bone of a fin- whale {Balanoptera muscidus, J. Miill. ; Rorqual de la 

 Médilerranée' G. Cuv.), fifty-three and two thirds feet long, and of a Greenland humpback 



(Krepokak, JBalcena boojjs, 0. Fabr., Megaptera lojir/imana, Gray), forty-three feet long, both seen 



from above, like that of the Greenland whale. In this position the articular surface of the lower 

 jaw of the Greenland whale (though by no means sharply defined) is visible in almost its whole 

 extent, whereas in that of both the rorquals it is completely hidden, in accordance with its 

 different direction already frequently mentioned. 



A not less conspicuous difi'ereuce is that the part of the bone adjoining the articular surface 

 is somewhat contracted in both the rorquals, so that the articular surface constitutes a 

 distinct condyle, and the part situated between it and the opening for the vessels and nerves 

 may be said to form a neck, whereas the lower jaw of the Greenland whale is thickest in this 

 place (see especially Plate V, fig. 2). Further, the part between the articular surface and the 

 great opening for vessels and nerves is extremely short in the Greenland whale compared with the 

 neck of the condyle in the rorquals; the distance between this opening and the coronoid 



