58 PROF. W. B. BENHAM ON THE OSTEOLOGY [Feb. 4, 



cokimn, and that the last (13th) rib is imperfectly ossified and 

 that the bone does not reach vip to its vertebra, except possibly 

 in very old individuals. 



The Sternum. 



As far as I have been able to discover, the sternum of this 

 whale has not yet received an adequate description. It was only 

 partially recovered by Wall, who gives but a short account of the 

 imperfect bone, while it is not referred to either by von Haast (4) 

 nor by Yan Beneden & Gervais. 



In the Parakanui specimen the sternum (PI. III. fig. 4) 

 consists of three sternebrse ; the first and second formed of a 

 single bone apiece, the last of a pair of small bones. Each sternebra 

 is capped by cartilage at each end, and the posterior end is bifid. 



The anterior end of the sternum is bent slightly upwards, bvit 

 otherwise the bones are flat ; the thickness increases from the 

 anterior end, where it is 8 mm., to the hinder end, which is 

 1 3 mm. in depth. The first two sternebrse have rounded lateral 

 margins, while this margin, in the case of last pair of bones, is an 

 abrupt slope downwards and outwards from the dorsal surface, 

 with a sharp but obtuse upper and a sharper acute lower edge — 

 the ventral surface of this last sternebra being wider than the 

 dorsal surface. 



There are four cartilaginous sternal ribs, measuring 90, 75, 60, 

 and 30 mm. respectively. 



The following measurements were made : — 



miliim. 



Total length, including cartilage 260 



Greatest breadth 155 



Least breadth 45 



Length of the first bony sternebra^ along the lower 



su.rface 90 



Greatest breadth 100 



Breadth at posterior end 60 



Thickness (dorso-ventrally) in middle 10 



Length of second bony sternebra 76 



Breadth at anterior end 54 



,, in middle 43 



„ at posterior end 51 



Thickness 12 



Length of each ossicle of the 3rd sternebra 31 



Greatest breadth 20 



Thickness 13 



The Hyoid. 



The hyoid is very briefly referred to by Wall, and rather more 

 fully described (with a figvire) by Yan Beneden & Gervais. 



1 Since the cartilages are only exceptionally preserved, the measurements of the 

 bones are also given. « 



