88 REPORT — 1841. 



of the articular extremity, in the degree of median constriction, and, espe- 

 cially, in the large size of the medullary cavity at the middle of the bone, 

 with the vertebral characters of the Poikilopleuro?i. 



Streptospondvlus, H. von Meyer. 

 Steneosaurus rostro-mcijor, GeofFroy. — 1 re Gavial d' Honjleur, Cuv. (vertebrce.) 



I am not aware that remains of this Crocodilian genus have hitherto been 

 recognised in any of the British strata. The very characteristic vertebrae 

 and jaws, of which the singular generic modifications Avere first described by 

 Cuvier,* were found in the Oxford clay formation at Honfleur, and in the 

 Kimmeridge clay at Havre. M. Hermann von Meyer likewise cites the lias 

 of Altdorf as a depository of the fossil bones of this genusf . 



The distinguishing vertebral characters are a ball and socket articulation 

 of the bodies of the vertebrae ; but the positions of the ball and cavity are 

 the reverse of those in the existing Crocodiles, the convexity being on the 

 anterior part of the vertebra, and the concavity directed backwards. In the 

 anterior vertebrae, which have the ribs articulated with the body, there is a 

 deep pit behind the costal articular surface ; the transverse process rises by 

 four salient ridges, one from each oblique process, and the two inferior and 

 principal ones from the base of the neurapophysis ; these ridges converge at 

 an acute angle as they ascend, and meet at the under part of the transverse 

 process, so as to include a triangular space, which is deeply concave. A 

 third salient ridge ascends from the fore part of the base of the neurapophy- 

 sis to the anterior oblique process, nearly parallel with the posterior of the 

 two last-mentioned ridges, so that the side of each neurapophysis appears as 

 if marked with the letter N in high relief. In the cervical and anterior dor- 

 sal vertebrae there are, instead of a single inferior spinous process, two ridges 

 which terminate each, in front, by a tubercle, as in the vertebra dentata of 

 the Crocodile. 



Streptospondylus Cuvieri, nob. — The first fossil here to be noticed, which 

 combines any of the above defined characters, is the anterior half of an an- 

 terior dorsal vertebra, in the collection of Mr. Kingdon of Chipping Norton : 

 it was found in the oolite in the vicinity of that town. 



The articular surfaces for the ribs are, as usual, close to the anterior part 

 of the body of the vertebra, and this terminates by a convex articular surface, 

 instead of being, as in the Crocodiles, concave : the second character is the 

 remarkably deep pit behind each of the costal articular surfaces. It is as if a 

 man had pressed his two thumbs forwards and inwards up to the first joint, 

 into the substance of the body of the vertebra, until their extremities had 

 nearly met. The aperture of each pit measui'es 1 inch by 10 lines. Sufficient 

 of the neurapophysial arch is preserved to show the depression which has 

 separated the two anterior ridges of its external surface ; but these charac- 

 teristic ridges, with the transverse, spinous and oblique processes, are broken 

 away. The medullary canal is compressed, and gives an oval vertical section, 

 1 inch 6 lines high, and 1 inch 2 lines wide. Both upper and lower surfaces 

 of the medullary canal are flat, and join the lateral surfaces at nearly a right 

 angle. There is a slight ridge along each side of the medullary canal, indi- 

 cating the neurapophysial suture, which extends here outwards and obliquely 



* Ann. du Mus. xii. p. 83, pi. x. xi. 



t The Saurian remains to which Prof. Bronn (' Lethsea Geognostica,' 1837, 8vo) has at- 

 tached the name of Leptocranius, cannot belong, as he supposes, to the present genus, if it 

 be true that the vertebrae are slightly constricted in the middle, and have both articular 

 extremities concave, as in the following description : — "Die dazu gehorenden Wirbel-Korper 

 in der jnitte wenig verengt, vorn und liinten sind concave Gelenk-flacUe." — p. 517. 



