Osteology of Loxomma Allmanni. 49 



body of the first cervical vertebra. The surface of the bone 

 in front of the articular cavity is smooth and slightly convex ; 

 its sides, somewhat rough, are overlapped a little by the 

 quadrate bones. 



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

 its transverse diameter is 1 T V inch, and its depth considerable. 

 In several other specimens of the basioccipital in Mr. Atthey's 

 collection its outline is more regularly circular ; these speci- 

 mens 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 hones can be distinguished as bounding by 

 their inner borders the basioccipital triangle and the cotyloid 

 cavity, and then running outward and backward to the pos- 

 terior external angle of the cranium, joining there with the 

 quadrate jugals and constituting the condyles for the mandi- 

 bular joints. The condyles are almost transversely placed, 

 but have a slight inclination forwards at their inner ends, 

 about 1£ inch 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 

 considerable part of the inner margin of the zygomatic arch ; 

 in front they appear to articulate with the basisphenoid and 

 ectopterygoids and perhaps also with the pterygoids ; but it is 

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

 the anterior terminations of the quadrate are hidden by the 

 ectopterygoid, 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 ptery- 

 goid ; 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 

 border of the same bones, by the malars, quadrate jugals, and 

 quadrate bones. 



The inferior surface of another skull in Mr. Atthey's col- 

 Ann. & Mag. N. Hist. Ser.4. Vol. xiv. 4 



