160 Mr. T. Attliey on Autliracosaurus Russelli. 



inner sides, invests them as in Loxomma. They are, at their 

 bases, oval in outline, the long diameter of the oval being 

 placed transversely to the line of the jaw. Above the alveolar 

 margin they are circular up to near their apices, where a ridge 

 exists on each side, giving the teeth a double edge. They are 

 longitudinally grooved, with flattened ridges between from the 

 alveoli up to near their apices. The whole surface of the teeth 

 is coated with a layer of enamel, which is thickest at the apex. 



Vertehrcv. — Thirty-six vertebrae were found in connexion 

 with the skull : — tirst, a small one, which has been pressed in 

 upon the skull between the supratemporal and the pterygoid 

 bones, and belongs probably to the upper part of the neck. 

 The remaining thirty-five are imbedded in two separate slabs 

 of shale : the smaller slab shows six vertebrae, all in a connected 

 series ; one of these is figured in Plate X. fig. 4. The larger 

 slab has twenty-nine vertebrae, also in a connected but con- 

 torted series, and lying nearly in their natm-al order, with their 

 dislocated and broken processes around and several ribs lying 

 beside them. 



The vertebrae are alternately large and small, well ossified 

 and presei-ved ; and the anterior and posterior surfaces of their 

 bodies are both somewhat concave. 



The bodies are broadly rounded and project downwards ; and 

 the space between the anterior and posterior surfaces is con- 

 cave from side to side, grooved, and pitted in the grooves ; the 

 under margin of the body is thicker than the margin bounding 

 the vertebral canal ; so that the spinal column at that part 

 must have been convex on its abdominal aspect : moreover the 

 bodies are peculiar in having the upper borders of their an- 

 terior surfaces projecting forwards in the form of a ridge, whilst 

 the lower borders of their posterior surfaces project in a similar 

 form downwards. The sides of the bodies are level with each 

 other : no facet is -vasible on the sides of the vertebral bodies 

 for the articulation of the heads of ribs ; but the facet on the 

 transverse process is distinct and large, but is not divisible 

 into an upper and a lower part. The nem*al canal is remarkably 

 small for the size of the vertebra. The transverse and zygo- 

 matic processes and the spinous processes arise, in the speci- 

 men figured, from the sides and top of the arch ; they are all 

 massive and of considerable size ; the transverse processes 

 have a length of 1^ inch, a breadth of y^ inch, and a thick- 

 ness of y% inch. The direction of the transverse process is 

 almost directly outwards ; that of the anterior pair of zygapo- 

 physes, which are rather concave, is upwards and slightly 

 inwards ; the posterior face downwards and outwards, and are 

 somewhat smaller than the anterior pair. 



