Skull of Tritylodon longzvus, Owen. 285 
and the septomaxillaries there is a gap, so that the nares 
are wholly separated only horizontally *. 
The suture separating the frontals from the parietals is not 
plainly to be seen ; but it is probable that it lies before the 
groove in the front of parietal bones. Unfortunately the 
foramen parietale could not be established in this groove by 
the new preparation ; but it seems to me still to be possible. 
Text-fig. 2 shows the lateral view of the skull from the left 
side, but the sutures have been completed from the right side. 
>» / \ 
a ‘N 
A: pmx, Ie. jl. 4 5 6 MX, 
Skull of Tritylodon, left side, nat. size. , probable sutures ; 
ene , possible suture (between fr. and prfr.). 
pa., parietal; prfr., prefrontal; fr., frontal; for./c., lacrimal foramen; 
na., nasal; sma., septomaxillary ; pr.pmz., process of the pre- 
maxillaries; pm.., premaxillary ; mz., maxillary ; /c., lacrimal ; 
ju., Jugal; osph., orbitosphenoid; 7.*, second upper incisor; 
1-6, postcanine teeth. 
The suture separating the parietal bone from prefrontal and 
bounding it from below is plainly indicated T and was observed 
* Broom’s contention that “there is no evidence that the nares have 
been separated by a complete internasal process of the premaxillaries” 
(comp. Broom, 1910, p. 763) has been confirmed by the new preparation, 
which shows a mode of division of the nares quite different from that in 
the theriodont Reptiles and without parallel in Mammals. 
+ As this suture is on the right side going up to the front part of the 
parietal bone, no doubt can be entertained about the lateral continuity 
of this whole bone on the right side (on the left side the bone is far more 
fractured in the middle than on the right side). So that Seeley’s suppo- 
sition that the two bones diverging from the median crest laterally are 
the posterior prolongations of the postfrontals must be wholly rejected. 
Comp. Seeley, 1895, p. 1026 s. 
