An Almost Perfect Skull of a Ncio Primitive Theriodont. 199 



I fail to find on the side of the snout any foramen by which the 

 infraorbital nerve could have had its exit. Most probably the 

 foramen is in that portion of the maxillary which lies below the 

 longitudinal ridge, and which in the specimen is very imperfectly 

 displayed. The absence of a foramen for the nerve, above the ridge, 

 would tend to confirm the idea that the greater part of the snout had 

 a horny or scaly covering. 



The jugal is a moderate-sized bone which forms almost the 

 whole of the lower and about half of the posterior margin of the 

 orbit. Below the orbit it is broad and flat and rests largely on the 

 posterior process of the maxillary. Behind the orbit is a strong 

 process which passes first mainly upwards and then inwards to meet 

 the postfrontal. The jugal sends a long process backwards which 

 passes underneath the squamosal and forms with it the temporal 

 arch. 



The postfrontal forms less of the postorbital arch than is usual in 

 Theriodonts and Anomodonts. Its postorbital portion, however, is 

 moderately strong. It passes outwards and slightly backwards and 

 .articulates wdth the front of the postorbital process of the jugal. 

 The inner part of the postfrontal passes inwards and backwards 

 behind the frontal and meets the parietal slightly in front of the 

 parietal foramen. 



The parietal is apparently single, though in front of the foramen 

 there is evidence of a median suture. So far as displayed the 

 parietal forms a prominent median crest, from which are given off 

 posteriorly two large post-temporal crests. It is difficult to be sure 

 how much of the parietal is covered by matrix, but its limits are 

 probably near those shown in the restoration (Fig. 5). In front the 

 parietal forms a strong interdigitating suture with the frontal, and 

 almost immediately behind the suture is the large parietal foramen — 

 large enough to have accommodated a well-developed pineal eye. 

 The large lateral crests of the parietal articulate near the posterior 

 •end of the temporal fosse with the squamosals. 



The squamosal is a moderately large bone. It bears a consider- 

 able resemblance to the squamosal in Ictidosuchus and also shows 

 some affinities with the squamosals of the Anomodonts and Mammals. 

 Internally it articulates with the parietal and forms part of the 

 posterior wall of the temporal fossa. Passing outwards it curves 

 forwards and forms the greater part of the temporal arch. The 

 anterior part of this zygomatic process rests on the posterior process 

 of the jugal. At the posterior part of the zygomatic arch the 

 squamosal forms a downward convex fanlike expansion which gives 

 articulation to the quadrate and also probably serves to some extent 



