THE 
GHOLOGICAL MAGAZINE. 
NEW SERIES. DECADE V... VOL. IV, 
No. X.— OCTOBER, 1907. 
(Spade MOI (VANE 72S On A era HS) 
oe 
I.—Evipences oF A MANDIBLE OF A NEW LABYRINTHODONT FROM 
THE Upper Karroo Breps or Care Cotony (PrycHospHENopoN 
BRrowNtl). 
By H. G. Szexry, F.R.S., F.G.8., King’s College, London. 
(PLATE XIX.) 
AM indebted to Mr. Alfred Brown, of Aliwal North, for the 
opportunity of describing a small fragment of a lower jaw of 
a Labyrinthodont which shows some unusual characters in the 
dentition and in the composition of the mandible (Pl. XIX, Fig. 1). 
Hitherto the evidence of the structure of the mandible has been 
imperfectly recorded in these South African reptiles. 
Mr. Brown’s specimen is a small transverse segment, probably from 
the left ramus, at some little distance behind the symphysis. This 
position may be indicated by an angular ridge upon the inner side, 
which is becoming more elevated as it extends forward. There is no 
suggestion of the original length of the mandible, which may haye 
been eighteen inches. The fragment is little more than an inch and 
ahalflong. In section the jaw is subquadrate, somewhat depressed, 
being two inches wide and an inch and a half deep. The external 
surface of the bones shows no trace of sculpture. From its slightly 
water-worn condition the specimen (Fig. 1) was probably obtained 
from the reconstructed bed at the railway station at Aliwal North, 
which yields Theriodonts and other fossils. 
The external bone is apparently vertical, traversed on the lower 
third by a deep longitudinal groove, in which there is a faintly 
marked suture. The dentary bone above the groove is slightly 
convex up to the alveolar margin, and shows what may be a sinuous 
impression above the groove. The bone below the groove, which may 
be infra-dentary, is well rounded on to the base. 
The base is flattened, but slightly convex from side to side, and is 
marked by a median groove which traverses a median inferior bone 
defined laterally by two irregular sutures. The base of the jaw is 
limited towards the inner side by a slight angular ridge. The inner side 
is divided into upper and lower flattened areas by the median angle 
already referred to. There is a longitudinal suture in the middle of 
the upper portion of the palatal surface. 
DECADE V.—VOL. IV.—NO. X. 298 
