﻿Yol. 64.] BRACHYBHYNCHUS FEOM THE OXFORD CLAY. 



347 



Measurements in millimetres. 



Length, of skull 



Length of praemaxilla 



Distance, prgemaxillas to nasals 



Length of nasals (median line) 



Length of frontal 



Length of prefrontal 



Length of parietal ridge to occipital condyle . . . 



Breadth across quadrates 



Breadth across postf rentals 



Breadth across frontal (at orbits) 



Breadth across prefrontals 



Breadth across nasals (at point of prsefrontals) 



Breadth across maxille (at point of nasals) 



Breadth across premaxillse 



Length of nasals (to point between prefrontal 



and frontal) 



Length of palatine 



Breadth of preirontal , 



Kg. 164. 



No. 165. 



700 



about 680 



155 



about 155 



15 







200 



220 



200 



185 



115 



117 



130 



120 



245 



224 



SOO 



270 



105 



115 



223 



216 



165 



160 



85 



85 



70 



— 



1 245 



230 



260 



265 



— 



80 



One measurement in Deslongchamps's description requires some 

 explanation. In Ms diagnosis of the species, he tabulates various 

 measurements which, if added together, give as the length of the 

 skull about 700 millimetres, which is the length of the larger 

 Eyebury specimen. On p. 337 (op. jam cit.) he says : — 



* La longueur totale de cette tete, depuis le condyle de I'occipital jusqu'a la 

 troncature anterieure du museau, est de 59 centimetres et de 62 environ, si on y 

 ajoute la region intermaxillaire qui est absente.' 



In the type-specimen the prsemaxillae are imperfect, only 40 mm. 

 of the total length being preserved. Dr. von Huene, of Tiibingen 

 University, who was in England lately and subsequently visited 

 Caen, very kindly measured this portion for me. This, with the 

 other measurements given, makes up the total length of 590 mm. 

 On p. 333, Deslongchamps estimates the total length of the prae- 

 maxillse to have been 150 mm., so that the missing portion was 

 110 mm. long, making the total length of the skull 700, not 

 620 millimetres, which is apparently a miscalculation. 



I shall employ throughout 3L superciliosus for purposes of 

 comparison, as it is the best-known species of Metriorhynchus. 



The first of the two skulls is one of the longest skulls of Metrio- 

 rJiynclius found in the Peterborough district, while both con- 

 siderably exceed M. superciliosus in width. The proportion of the 

 breadth (taken across the prssfrontals) to the length is, in this case, 

 roughly speaking 1 : 3*2, while in M. superciliosus it is 1 : 4*5. 

 Considering that a large skull of the latter species measures 

 670 mm. in length, this may be said to constitute a very great 

 difference between them, apart from other variations. Despite the 

 length of the skull of M. hrachyrhynclms, the great breadth across 

 the prsefrontals and postfrontals gives at first sight an impression 



