ANATOMY OF MEGAPTERA LONGIMANA. 181 



is present in B. musculus, running on from the lower notch, for 

 2 inches as a shallow triangle ; it is absent in Megaptera. 



Condyle. — The condyle proper is to be distinguished from 

 the more projecting tuberosity below it. The differences on 

 the condyle are — (1) The obliquity, downwards and outwards, 

 is much greater in B. musculus, in adaptation to the corre- 

 sponding obliquity of the neck, above-noted. (2) In B. mus- 

 culus the outer edge of the condyle projects forwards, at its 

 lower half, as a broad thick tongue, overhanging the surface of 

 the neck, receiving the finger between them. In Megaptera, 

 although the outer side of the condyle projects more than in 

 B. musculus, there is no abrupt or forward projection, only the 

 thick outer side of the condyle projecting uniformly. (3) The 

 condyle on the inner side in B. musculus projects uniformly, 

 without sharp edge, in its whole height here (about 7 inches). 

 In Megaptera it projects less, has a rough sharp edge at the 

 middle, and is short vertically (about 5i inches). (4) The 

 groove between the condyle and tuberosity, on the inner side, 

 is in Megaptera situated at the mid-height of the end of the 

 bone, is well defined, large enough to receive the end of the 

 thumb, and is directed obliquely upwards and forwards, In B. 

 musculus it is a wide valley, 4 inches wide, f inch deep at the 

 deepest part, which is some Avay below the middle of the entire 

 end of the l)one. (5) The separating groove on the outer side 

 is also more definitely marked in Megaptera, both above, by the 

 more abrupt projection of the condyle, and below, by the more 

 outward position of this part of the tuberosity. 



The differences on the tuberosity are not very definite, except 

 in regard to the separating grooves above noted; but it projects 

 more laterally in Megaptera than in B. musculus, both inter- 

 nally, as a sharp forward-ascending edge (entirely wanting in 

 B. musculus), and on the outer side as a broadly- projecting 

 outer edge to the bone below the condyle. In B. musculus it 

 is wanting below the inner third of the condyle ; in Megaptera 

 it extends across the whole breadth of the condyle, at the inner 

 part as a narrow ascending edge. 



Body. — The proportions of the body of the mandible in 

 Megaptera and B. musculus are seen in the table. The actual 

 depth of the curve is nearly the same in both, but as this depth 



