﻿348 ME. E. THUELOW LEEDS 01^ METBIORHYNCHUS [Aug. 1 908, 



of shortness, as both skulls present in a remarkable degree the 

 feature upon which Deslongchamps founded his species. In I^o. 164 

 there is only an interval of 15 mm. between the posterior end of 

 the prsemaxillae and the anterior point of the nasals, while in 

 jN^o. 165 even this interval is wanting ; and it is indeed a question 

 whether the point of the nasals does not pass beyond the prae- 

 maxillae, although a slight displacement of the bones through 

 crushing precludes any definite assertion. 



The skull widens without interruption from the praemaxillae to 

 the postfrontals, the greatest width being attained at the posterior 

 edge of the orbits, from which point it again decreases in width, 

 though only by the amount of 50 mm. measured across the widest 

 point of the quadrates. There is entirely lacking the long, uniformly- 

 wide portion of the maxillae, which is to be seen in Metnorhynchus 

 sujperciliosus. In this respect 3£. hrachyrliynclius is more comparable 

 with M. Moreli, which, as Deslongchamps points out, increases in 

 width in the same manner. 



The prsemaxillse are stoutly-made bones, 155 mm. long, 

 Deslongchamps's estimate being about correct, and 70 mm. broad at 

 their greatest width. So far as can be judged from the one com- 

 plete praemaxilla, they were more swollen than those of M. sujoer- 

 ciliosus ; and certainly the constriction behind the 3rd tooth, in which 

 the 4th tooth of the mandible fitted, is much more marked than in 

 the latter species. Again, the suture at its junction with the maxilla 

 is different. In M. superciliosus it runs in a gentle uninterrupted 

 curve from the alveolar border to the posterior point of the prae- 

 maxilla on the median line ; whereas in M. brachyrhynclius it runs 

 at first at a little more than a right-angle towards the middle for a 

 distance of about 45 mm., from which point it turns backwards at a 

 sharp angle, so that the posterior end of the praemaxilla, instead of 

 being practically triangular, consists merely of a narrow point. As 

 in other species of 3£etriorhynchus, there are only three teeth in the 

 praemaxilla. 



Maxilla. — As is of necessity the case, this is the species of 

 Metriorhynchus in which the maxilla shares the least in the for- 

 mation of the median dorsal line, for in No. 165 it is entirely 

 excluded by the nasals, and in No. 164 for all but a distance of 

 15 mm. The anterior end of the maxilla is stunted in agreement 

 with the form of the praemaxillary suture, as is clearly shown in 

 Deslongchamps's figure (pi. xxiii, Ic). 



The teeth in the maxilla are 18 in number, making the dentary 

 formula for the upper jaws 42, which is the number stated by 

 Deslongchamps. The alveoli are much larger than in 31. super- 

 ciliosus, and are divided one from the other by wider interalveolar 

 ridges. 



Dr. G. von Arthaber ^ doubts the correctness of the dentary formula 



1 Beitr. zur Palaont. & Geol. CEsterr.-Ungarns, &c. vol. xix (1906) p. 293. 



