320 MR. 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 fissure, 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 drown 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 Tostrum, 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.q) 
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 fibrous 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 53," 
to 7/9" 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 Rudimentary maxillary 
having been broken off. The pulp-cavity is completely closed at tooth, nat. size. 
the base of the tooth, which, in most of the specimens, is more or less surrounded by 
rough, irregular, spiculated outgrowths. 
Fig. 1. 
* A 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 Pl. LVII. fig. 2), is not ossified in the foetal skull figured 
in Husley’s ‘ Elements,’ where the pterygo-palatine suture appears straight and transverse. 
