Professor H. G. Seeley—New Cape Labyrinthodont. 4385 
bone it rises above the level of the dentary on the superior dentigerous 
surface, where it is roughened and vascular, forming a supporting 
outer ledge for the teeth which it carries, which is of the same kind 
as the external elevated alveolar border of the dentary bone. The 
teeth, however, are smaller; they are not so close set in this 
specimen ;' each has a transversely ovate base, and is implanted in 
a shallow conical pit or socket, which the base of the tooth does not 
completely fill, for a groove extends round the base of the inner side 
of the tooth. The base is invested with an osseous cement, above 
which the crown shows vertical grooves of the same type as are seen 
upon the row of teeth in the dentary bone. At one end of the 
specimen a fracture passes through the base of a tooth, and shows the 
same folded structure in these teeth as in the parallel dentary tooth ; 
next is a large empty socket, the base of which is not clean from 
matrix ; this is followed by a broken tooth in position; and lastly, 
after an interval, the terminal fracture passes through the middle of 
a clean empty conical socket. The teeth of this inner row appear to 
diminish in size as they extend backward. 
As the teeth are broken to the level of the alveolar margin of the 
dentary I availed myself of the opportunity to obtain a transverse 
section of a portion of a tooth on the dentary bone at the level of the 
alveolar border where the tooth is ovate. In microscopic enlargement 
the labyrinthic structure is much less folded and simpler than in any 
other tooth from these rocks which I have examined (Pl. XIX, Fig. 2). 
In the Museum of the University of Munich a second specimen of 
the mandible of the same species is preserved, collected at Middelburg 
in Cape Colony. The late Professor K. v. Zittel placed it in my 
hands to complete this description. The Munich fossil is a fragment 
from the right ramus of the mandible, two and three-quarter inches 
long. It exactly corresponds in its position in the jaw with the 
fragment of the left ramus from Aliwal North. The anterior fracture 
is oblique, the posterior fracture is vertical. The sutures are not 
shown upon the black bone of these ends. The fossil indicates a long 
narrow skull, with a short mandibular symphysis (Pl. XIX, Figs. 3, 4). 
The Middelburg specimen is from a soft matrix, which has been 
sufficiently removed to show the forms of the teeth and their im- 
plantation. The dentary series of teeth gives evidence of nine teeth 
in a length of two and seven-tenths inches, so that each tooth occupies 
three-tenths of an inch, as in the other specimen, and the basal 
attachment is eight to nine-tenths of an inch wide. Five teeth are 
lost, and as these are consecutive the bases are seen to be divided 
from each other transversely by ridges, forming shallow sockets (Fig. 4), 
rather more pronounced than those sometimes seen in the not dis- 
similar but deeper groove which carries the teeth in Jchthyosaurus. 
The crowns are better preserved, and have a singularly compressed, 
sharp, triangular, wedge-shaped aspect, as though used for catching 
fish. They are flattened laterally, rounded on the narrow outer and 
inner aspects, which are straight and converge upward to a sharp 
point. Hach of these wedge-shaped teeth was about one inch and 
a quarter long, but only one shows the extremity of the crown. Seen 
from the end, the contour of a tooth is not unlike a large longitudinally 
