SKTJLL AND OTHEK BONES OF LOXAMHA ALLMANNI. 209 



The articular cavity, much compressed, has au oval contour ; 

 its transverse diameter is one and four-tenths of an inch, and its 

 depth considerable. In several other specimens of the basioc- 

 cipital in Mr. Atthey's collection its outline is more regularly 

 circular ; these specimens are of various sizes, having belonged 

 to examples of different ages. 



Behind and below the cotyloid cavity, are partially seen the 

 facets of the exoccipitals for articulation with the neural arch of 

 the atlas. The foramen magnum is not visible in this view. 



The quadrate tones can be distinguished as bounding by their 

 inner borders the basioccipital triangle and the cotyloid cavity, 

 and then running outward and backward to the posterior exter- 

 nal angle of the cranium, joining there with the quadrate jugals 

 and constituting the condyles for the mandibular joints. The 

 condyles are almost transversely placed, but have a slight incli- 

 nation forwards at their inner ends, about one inch and a quarter 

 long, rounded from before backwards, and their ends somewhat 

 raised above the middle, which is slightly depressed. 



The quadrates at their internal ends are broad, and become 

 gradually narrower as they are traced outwards to the condyles, 

 where they are again enlarged. Their outer borders form a con- 

 siderable part of the inner margin of the zygomatic arch ; in 

 front they appear to articulate with the basisphenoid and ectop- 

 terygoids and perhaps also with the pterygoids; but it is im- 

 possible clearly to make out these parts. On the left side the 

 anterior terminations of the quadrate are hidden by the ectop- 

 terygoid, which has been dislocated and thrown over them. 



The ectopterygoids complete the sides and back part of the bony 

 palate by uniting with the palate-bones and the pterygoid ; but 

 the lines of connexion are not visible. 



They are rather broad and strong and articulate behind with 

 the quadrates ; directed thence outwards and forwards they are 

 sutured to the posterior internal extremity of the palate-plates 

 of the maxillaries. 



The malar or zygomatic arches, as seen from below, are thus 

 circumscribed by the ectopterygoids, the posterior ends of the 

 palate-plates of the maxillaries, and a portion of the alveolar 



