PROF. OWEN ON THE ENDOTHIODONT REPTILIA, 559 
seem not to have a parallel continuation backward of the inner row, 
are circular in section and have not been indented through such 
relative position. Nor is that position, where it obtains, such as to 
suggest that the inner row could push out the teeth outside them. 
I conclude, therefore, that the three rows of palatal teeth + indicated 
in the type example of Endothiodon bathystoma were normally 
opposed by three rows of similarly shaped and slightly smaller teeth 
of the lower jaw. 
ENDOTHIODON UNISERIES, Ow. 
This species is founded upon the fore half of a skull including 
nearly the same parts and proportions thereof as the fossil indicative 
of the genus (op. cit. pl. lxvii.), but it has not been subject to 
the same pressure and distortion. It is of smaller size and differs 
more markedly in haying but a single row of teeth on each side of 
the palate, which some may deem to justify a distinct generic appel- 
lation. It is, however, a reptile of the same singular and well- 
marked type as is exemplified by the fossils of Kndothiodon bathy- 
stoma. As in that species, the trenchant alveolar border of the 
upper jaw commences with a caniniform process (Pl. XXVII. fig. 
2, ¢), to the fore and inner part of which the premaxillary (ib. 22*) 
contributes a larger share than is indicated by the suture shown in 
the section of this quasi-canine in Hndothiodon bathystoma (op. cit. 
pl. Ixvii. fig. 6). 
Of this process on the right side of the present species I also 
made a transverse section (fig. 3, 21*, z2**), and exposed only the 
osseous tissue, of which the outer part was of almost dentinal hard- 
ness, and the inner part closely or minutely cancellous. This pro- 
cess, howsoever covered in the recent reptile, would be used as a 
dental weapon, and have the same title to be called ‘tooth’ as that 
part in the beak of the Falcon. 
The trenchant border of the maxillary, continued from the pro- 
portion which it contributes (figs. 2 & 3, 21*) to the caniniform 
process, describes a slight curve convex downward, concave, out- 
ward, and gradually gains in thickness—though this may be partly 
due to abrasion of the original margin, which at the hinder third of 
both right and left maxillary exposes the same dense texture as in 
the caniniform process. 
The premaxillary contributes the anterior third of the outer and 
the whole of the inner half of this process (fig. 3, 22**), being 
continued backward along the inside of the maxillary portion (ib. 
21**), The suture exposed in the section (fig. 3, between 21* & 22*) 
extends upon the palatal surface of the skull along the fore border 
of the maxillary, 21’, and palatine, 20', plates in a sigmoid course 
curving backward to the fore part of the vomer, 13. The premaxillo- 
vomerine suture is shown at 13’, fig. 3, Pl. XXVII. The interpre- 
maxillary suture is obliterated, and the confluent pair of bones con- 
t The pulp-cavity exposed by section of the palatal teeth, in the multiserial 
arrangement, shows a bright red tint, indicative of the ferruginous colouring- 
matter of the blood, in the type specimen of Lndothiodon Beige 
Q 
