Prof. H. G. Seeley on Euskelesaurus Brownii. 337 



it, so that it excavates a wide concavity in the angular bone, 

 and the horizontal plate passes into the inferior margin of the 

 jaw, which it presumably deepens, though this is not evident 

 from the condition of preservation. The entire length of the 

 fragment is 13^ inches, of which 10 inches are in advance of 

 the anterior margin of the articulation. 



In close proximity with the articular end of the jaw already 

 described, and in the same line with it, but without the inter- 

 vening bone being preserved, was the anterior dentary part 

 of the lower jaw, almost complete at its extremity. It 

 measures a foot in length, and presuming that the two pieces 

 are portions of the same jaw, it would probably have been 

 fully 30 inches long when perfect ; so that it would not be 

 inferior in size to Megalosaurus, Ceratosaurus, and types 

 which present a similar dentition. There is no proof that it 

 is the lower jaw of a species of Euskelesaurus, since the teeth 

 are more slender than those already described in the maxillary 

 bone. The number of teeth in the jaw is small, and they do 

 not appear to have exceeded the number in the maxillary bone 

 of Euskelesaurus Brownii. The jaw is remarkable for the 

 evidence it gives of composite character on its inner side. A 

 bone extends along the inner alveolar border, which is distinct 

 from the dentary, forms the inner half apparently of the 

 alveoli, and makes more than half the depth of the jaw, and 

 appears to extend almost to its anterior extremity ; and poste- 

 riorly there is a groove between this splenial element above 

 and the thickened basal ridge of the dentary bone, which 

 appears to have lodged another bone, presumably the forward 

 tapering extremity of a large coronoid. Professor Marsh 

 remarks that in Ceratosaurus the splenial bone is large, ex- 

 tending forward to the symphysial surface, and forming in 

 that region a border to the upper margin of the dentary bone. 

 There is one remarkable character, however, in which this 

 jaw differs from almost all known Saurischia — in the jaw be- 

 coming deeper as it extends forward. At the hindermost 

 tooth-socket preserved the depth is about 3 inches, but within 

 3 inches of the fractured anterior extremity the depth is 

 3| inches. The jaw is remarkably straight and compressed 

 from side to side. The width at the hindermost tooth-socket, 

 9 inches from the front, is 1^ inch ; but it becomes a little in- 

 flated on the outer side anteriorly, though this character may 

 be partly the result of distortion. 



The external surface is vertical, somewhat rugose, with 

 vascular impressions, and with a row of shallow pits corre- 

 sponding to the teeth an inch below the alveolar border. 

 There is a convex rounding of the side on to the alveolar 



