﻿350 ME. E. THUELOW LEEDS ON METRIORHYNCHUS [Aug. 1908, 



Deslongchamps in his figure (pi. xxiii) makes this suture com- 

 mence more anteriorly on the interior border of the orbit. As this 

 seemed to be almost the only difference that I could find between 

 Deslongchamps's specimen and those at present under consideration, 

 I asked Dr. von Huene to investigate this point for me, and I am 

 deeply indebted to him for the trouble that he has taken. He wrote 

 to me that the suture commenced at the centre of the orbit. This 

 has now been further confirmed by an interesting letter which I have 

 received from Prof. Bigot. He writes with regard to the photo- 

 graphs that he sent : — 



* Les traits noirs marquent les sutures des os telles qu'elles ont ete tracees par 

 Deslongchamps, mais M. von Huene a du vous dire que les frontaux anterieurs 

 ne sont pas exactement limites en arriere sur la figure de Deslongchamps, qui 

 a pris une cassure pour une suture. J'ai fait la correction a I'encre sur 

 I'epreuve.' 



On the photograph Prof. Bigot has drawn the suture commencing 

 at the same place as in the two skulls before me, the result being 

 that it traces, with but unimportant variations, the course which I 

 have described above. I say ' unimportant variations,' as I have 

 found in examining numerous skulls of M. superciliosus that 

 variations are always to be found in the line of this suture, the 

 sutures of the two prsefrontals in the same skull even sometimes 

 differing slightly, with one exception, namely : — that the point of 

 commencement of the suture on the orbit is always the same within 

 a distance of 2 or 3 millimetres : that is to say, that, while in 

 Metriorhynchiis hracliyrJiynchus the suture starts at the centre of 

 the orbit, in M. superciliosus it commences at, or very close to, a 

 line drawn across the anterior border of the orbits. 



In consequence of the correction made above, Deslongchamps's 

 description of the frontal (ojo. cit. p. 334) no longer holds good : — 



^ triangulaire en avant, quadrilatere en arriere, grace a deux angles rentrants 

 que determinent, sur les cotes, le developpement inusite des frontaux anterieurs.' 



A reference to that author's figure (pi. xxiii) will elucidate 

 this description. In reality, the frontal is triangular in form 

 throughout. Another result of this correction is that the portion 

 of the border of the orbit occupied by the frontal is reduced. 

 Deslongchamps gives it as 50 mm., whereas the distance from its 

 junction with the postfrontal to the suture of the prgefrontal is 

 between 30 and 40 millimetres in the specimens now described. 



Deslongchamps states that the praefrontals are 60 centimetres 

 wide, and are less developed in width than those of M. superciliosus 

 and M. liastifer, being more similar to those of M. Blainvillei and 

 M. Moreli. In the type-specimen the prsefrontals are imperfect, 

 and it is evident that Deslongchamps bases his estimate of their 

 width on a restoration such as appears in his figure. This restor- 

 ation is made to correspond with that of the temporal orbits, which 

 are too narrow. The true breadth of the prsefrontals is 80 mm., 

 while in M. superciliosus 60 mm. appears to be an extreme width, 

 the usual width being about 55 mm. Deslongchamps gives no 



