320 



ME. W. H. FLOWER ON THE OSTEOLOGY OF THE SPERM-WHALE. 



unite in the middle line for a space of 11", presenting a broad flattened surface. 

 Behind this they become thin and separate from each other, the usual notch on their 

 posterior free margin being represented by a deep narrow fissui-e, of which the sides are 

 almost in contact, except at the bottom, where it widens into a triangular space. 

 The external surface of the pterygoid is slightly hollowed, as in Hyperoodon and the 

 Ziphioids ; but there is no reflexion of the margin to form an outer bony wall to the 

 postpalatal air-sinus, as in the ordinary Dolphins. 



The palate bones are largely apparent on the surface, much more than in Hyperoodon. 

 The outline of the exposed surface of each is convex in front, and concave behind, where 

 it is overlapped by the pterygoid*. The vomer is widely exposed for the whole of its 

 length in front of the palate bones. A narrow strip of the premaxillary becomes 

 apparent between the vomer and the maxillary near the middle of the rostrum, and 

 gradually widens forwards. 



The greater part of the under surface of the rostrum is formed by the broad, convex, 

 triangular maxillary — generally smooth, but having a strongly marked groove {d.g) 

 running longitudinally near the middle (evidently the remains of the dental groove), 

 enlarged at intervals by the foramina for the passage of the branches of the superior 

 maxillary nerve and artery, which supply the thick flbrous covering of the palate. It 

 is probable that the rudimentary teeth concealed in the gum of the upper jaw, the 

 existence of which has been repeatedly affirmed and denied, are situated in or near this 

 groove. 



Ten such teeth were sent with the present skeleton. Some of 

 these are of hard, solid, yellow ivory ; but others are white and 

 friable, splitting into concentric layers, as if they had been cal- 

 cined. They are all between 2" and 3" in length, and about |" 

 in diameter at the thickest part. Some are straight, but most of 

 them are more or less curved, one forming a complete half circle. 

 All have a distinct blunt conical crown, ^" long and from ^" 

 to ^" of an inch in diameter, separated by a slight constriction 

 from the expanded root, which constitutes the largest part of the 

 tooth. The surface of the crown differs from that of the fang in 

 being slightly granulated. It shows no signs of attrition ; but 

 the apex in all is roughly truncated, giving the appearance of 

 having been broken off". The pulp-cavity is completely closed at 

 the base of the tooth, which, in most of the specimens, is more or less surrounded by 

 rough, irregular, spiculated outgrowths. 



Fig. 1. 



Rudimentary maxillary 

 tooth, nat. size. 



* h. thin and narrow plate of the pterygoid, with rounded margin projecting forwards, and partially covering 

 the palatal, both in the adult and young skull (see PI. LVII. fig. 2), is not ossified in the foetal skull figured 

 in Huxley's ' Elements,' where the ptcrygo-palatino suture appears straight and transverse. 



