THE PHYTOSAURIA OF THE TRIAS 135 



orbits. They are bounded on the inner side from front to back by 

 the f rentals, the parietals, and the squamosals. The anterior 

 sutures of the frontals are not evident. 



The frontals appear to extend forward to within 68 mm. of the 

 nares. This would give them a length along their median union of 

 about 68 mm. They form the upper borders of the orbits and 

 join the prefrontals and nasals in front. Their anterior margin 

 seems to form a slight concavity into which the posterior ends of 

 the nasals extend. 



The prefrontal sutures are not certain; these elements seem to 

 be small, approximately quadrangular in outline, and form the 

 upper anterior borders of the orbits. 



The lachrymals^ unite with the maxillae to exclude the nasals 

 from taking part in forming the borders of the antorbital vacuities. 

 Their downward extent and union with the maxillae are uncertain. 



The jugal forms the lower postero-lateral border of the skull. 

 At its anterior end the jugal sends forward a splinter-like process 

 that forms the lower posterior border of the antorbital vacuity. 

 It also sends back from the anterior upper side a process that 

 unites with the lachrymal in front and the postorbital behind, and 

 thus forms the lower anterior border of the orbit and the anterior 

 half of the lower temporal fenestrae boundaries. 



The quadrato jugal connects broadly with the jugal below. Its 

 suture with the squamosals is not distinguishable. The sutures 

 between the nasals, the septomaxillae, the maxillae, and the pre- 

 maxillae cannot be determined with certainty. In all probability 

 the relations are much the same as in another form to be described 

 later (see Fig. 4). 



The premaxillae are produced into a long, slender, subcylindrical 

 snout much like that of Mystriosuchus. Viewed dorsally it tapers 

 gradually from the cranium proper to a point near the extremity, 

 from a width of 94 mm. at a distance of 140 mm. in front of the 

 antorbital vacuity, to 47 mm. Near the tip the rostrum expands 



' E. Gaupp has attempted to show that the so-called "prefrontal" of reptiles is 

 homologus with the mammalian lachrymal and has suggested the name " adlachrymal" 

 for the element previously called the lachrymal in reptiles (Anatom. Anz., XXXVI, 

 1910). According to Gregory (1913), however, this homology is in nowise proven. 

 In this paper the writer adheres to the old nomenclature. 



