PROF. OWEN ON THE ENDOTHIODONT REPTILIA. 557 
43. On the Exporntoponr Repriiia, with Evidence of the Species 
ENDOoTHIODON UNISERIES, Ow. By Professor Owrn, C.B., F.R.S., 
F.G.8., &. (Read May 28, 1879.) 
[Puate XXYVHII.] 
In the ‘Descriptive and Illustrated Catalogue of the Fossil Rep- 
tilia of South Africa in the Collection of the British Museum’* a 
genus Hndothiodon and the species bathystoma were founded on a 
portion of a skull and of a mandible from the Trias of Gouph? (p. 66, 
pls. Ixvi. & Ixyii.). The alveolar border of the upper jaw was sub- 
trenchant, with a caniniform process on each side, as in Oudenodon. 
A section being made of this part, there was exposed, as in Ou- 
denodon magnus (op. cit. p. 56, pl. liv., c’), a close osseous tissue, 
without trace of a canine or of a socket for any rudiment or germ of 
tooth (op. cit. p. 66, pl. lxvi., ¢’ c'); whence I inferred that such 
premaxillo-maxillary margin might have been sheathed, asin Chelonia, 
with horn. The opposing outer border of the portion of the man- 
dible presented a similar toothless, subtrenchant character, but was 
extended in an unusual degree internal to such margin, giving great 
transverse thickness to the rami from the symphysis as far backward 
as the dentary element was preserved. 
On the palatal surface of the crushed cranial fragment a single 
median palato-narial aperture was exposed, and some small cylin- 
droid teeth appeared to be scattered in two or more rows on each 
side of the palate (bcd. pl. Ixvii. figs. 1 & 4). Sections of the man- 
dible showed that such teeth had been opposed by similar ones 
developed in the thick inner border internal to the edentulous 
alveolar margin. 
In the anterior portion of a mandible of the same species of Hn- 
dothiodon subsequently discovered at ‘‘the Kloof” under the “ Nieu- 
woeldt range” of the ‘Gouph’ tract, and transmitted by Thomas 
Bain, Esq., I had a horizontal section made of the right dentary, and 
exposed three series of teeth or portions of them, affording satisfac- 
tory confirmation of the dental character which the more fragmen- 
tary fossil previously at my command had less completely indicated 
(op. cit. p. 66, pl. Ixvii. figs. 2 & 5). 
In the section figured (Pl. XX VII. fig. 1) the innermost row of 
mandibular teeth, eleven in number (1-11), commences 1 inch 9 lines 
behind the foremost part preserved of the symphysis (the apex of 
which is wanting), and the row terminates 4 inches from that part. 
The form of each tooth is subcircular, the diameter varies from 6 to 
4 millims. ; the hindmost tooth shows the smallest size, the other ten 
* Ato, 1876. ; 
+ A district bounded on the north by the Nieuwoeldt plateau, on the south 
by Zwarte Bay, on the cast by Beaufort West, and on the west by Karoo 
Poort. 
Q. J. G. S. No. 140. 2a 
