Skull of Tritylodon long?evus, Owen. 



285 



nnd the septomaxillaries there is a gap, so that the nares 

 are wholly separated only horizontally *. 



The suture separating the fiontals 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 

 fiide, but the sutures have been completed from the right side. 



Fig. 2. 



pr pmx 



osphi 



It 



pmx. 



/^. 



5 6 



, probable sutures ; 



Skull of Tritylodon, left side, nat. size. 



-.-.-, possible suture (between /r. and^;//-.). 



pa., parietal ; 2J//r., prefrontal;/?-., frontal ; /or ic, lacrimal foramen; 



72«., nasal ; s??^.^■., septomaxillary ; ^r.^m.r., process of tbe pre- 



maxillaries; ;???i.r., premaxillaiy ; m.r. , maxillary ; /c, lacrimal ; 



' ;m., jugal; osph., orbitospheuoid ; «.^, second upper incisor; 



1-6, postcanine teeth. 



The suture separating the parietal bone from prefrontal and 

 bounding it from below is plainly indicated f and was observed 



* Broom's contention that " there is no evidence that the nares have 

 been separated by a complete interuasal process of the premaxillaries " 

 (comp. Broom, 1910, p. 7(53) has been conlirmed 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. 



t 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, 1896, p. 1026 s. 



