﻿6 FOSSIL REPTILIA OF THE 



applied itself to the anterior edge of the ascending process of the maxillary, or to that of 

 the premaxillary ; in other words, whether the maxillary entered into the formation of 

 the outer nostril, as in Lacertilia, or was excluded therefrom, as in CrooodUia. 



The present Dinosaurian skull supplies this test and shows its correspondence with 

 the Crocodiles ; there is, nevertheless, a touch of the Lizard. For the body or jaw- 

 part of the premaxillary (PI. I, fig. 9, 22) sends upward not only the process from its hinder 

 part (22 x ), applying itself to the outer border of the fore-part of the nasal (15) and 

 excluding therefrom the maxillary (21), but it also sends upward a more slender process 

 from the fore-part, which terminates in a point wedged between the ends of the nasals 

 and dividing the right nostril ( n ) from the left, after the lacertian type. Yet, again, the 

 Crocodilian affinity is here manifested, for the premaxillaries are not confluent and 

 the dividing process is not a single and symmetrical one, as in Iguana, Varanus, and 

 most Lizards, 1 but is bisected by the medial suture or cleft dividing the right from the 

 left premaxillary. The premaxillary thus, in the main, adheres to the type of that of 

 the Crocodile, circumscribing all that part of the nostril which is not due to the nasal 

 bone itself, and excluding the maxillary from the boundary of the respiratory opening. 

 The application of the outer process of the fore-end of the nasal to the anterior edge of 

 the ascending process of the maxillary 2 could only be predicated by one mistaking a 

 crack of the premaxillary for the suture. The ascending process (PI. I, fig. 9, 22") with 

 which the nasal articulates at the outer part of its fore-end belongs to the premaxillary as 

 well as does the inner process of the same end of the nasal bone. 



The premaxillo- maxillary suture extends from behind the sixth obvious premaxillary 

 tooth for the extent of nearly an inch, with a slight curve convex forward, between the 

 two main elements of the upper jaw. The maxillary and premaxillary have been slightly 

 separated from each other along this suture by the force which has fractured both bones ; 

 but the margins of the suture show its true nature and distinguish it from the fractures, 

 especially those on the body of the premaxillary, one or other of which must be adopted 

 for a suture on the hypothesis of the hinder ascending process (22") belonging to the 

 maxillary bone. 



Of the six premaxillary {teeth in place the foremost alone (PI. I, fig. 9, i) has the crown 

 entire ; its outer surface is convex across and lengthwise, most so along the middle, trans- 

 versely, the main or mid-ridge of the Iguaaodontal teeth being thus indicated. The margins 

 are also slightly relieved (PI. II, fig. 18, magn.) and converge at an acute angle to a sharp, 

 slightly incurved, apex ; the enamel is minutely punctate. Neither in the right nor the left 

 deflected part of the premaxillary, anterior to the pointed tooth, is there any trace of 

 socket or fang. It would seem that this end of the premaxillaries was edentulous, like 

 the corresponding slope of the symphysiai part of the mandibular rami to which it was 



1 Hatteria (llhynchocephalus) is an exception (' Phil. Trans.,' 1862, plate xxv, fig. 5, 22, p. 467). 



2 " The outer, in like manner, applies itself to the anterior edge of the ascending process of the maxillary 

 and forms a part of the outer boundary of the nostril. " — Huxley, ut supra, p. 4. 



