90 REPORT — 1841. 



Norton, a portion of a broad flat bone, with a convex, rough, articular labrum, 

 nearly two inches thick, and of a fine cancellous structure, and fragments of 

 long bones, with large medullary cavities and compact outer walls, of which 

 the thickness equals about one-third of the diameter of the medullary canal. 



A more perfect specimen, referable to the present genus, is a posterior 

 dorsal vertebra from the jet-rock (lias shale) near Whitby, and forms part 

 of the collection of fossils of Mr. Ripley, surgeon of that town. 



It is much more complete than the preceding specimen, wanting only the 

 spinous and transverse processes ; there is a slightly raised oval surface for 

 the articulation of the head of the rib, on each side of the body, at its upper 

 and anterior part, in the corresponding situation with that for the head of 

 the rib on the four anterior dorsal vertebrae in the existing Crocodiles : this 

 surface in the Whitby vertebra is relatively smaller and lower down than in 

 the larger specimen of Streptospondylus from the oolite. 



The present specimen nearly corresponds in size with the dorsal vertebrae 

 of the Honfleur Streptospondylus described by Cuvier*, as will be seen by 

 the following admeasurements : — 



Length, or antero-posterior diameter of body 

 Transverse diameter of articular surface . . 

 Transverse diameter of middle of body . . 



The principal character of the vertebrae of Streptospondylus, viz. the an- 

 terior ball and posterior cup, is unequivocally demonstrated in this specimen 

 by the presence of the oblique processes, which determine the anterior and 

 posterior extremities of the vertebra ; the two articular surfaces which look 

 upwards and inwards correspond with the convex extremity of the body of 

 the vertebra ; while those on the oblique processes, which look downwards 

 and outwards, overhang the extremity of the body of the vertebra, which 

 is excavated by a moderately deep and regular concavity. 



To judge from the figures of two of the vertebrae of the Streptospondylusf 

 from Honfleur, the characteristic fossa on each side of the body becomes 

 shallower, and situated nearer the middle of the side of the body as the ver- 

 tebrae approach the tail ; but the lateral fossae present both these modifications 

 in the Whitby vertebra, which, from the articular surface of the rib, would 

 seem to have come from the anterior part of the dorsal region of the spine. 



This vertebra presents the minor generic characters of the Streptospon- 

 dylus in the length of the body, its lateral compression and inferior conca- 

 vity, the two extremities being expanded to form the articular surfaces. 

 The non-articular surface is smooth, except near the margins of the articular 

 extremities. The line of the haemapophysial suture extends horizontally the 

 whole length of the centrum. The two characteristic lateral buttress-like 

 ridges rise from the two extremities of the base of the neurapophysis, and 

 converge to the under part of the base of the transverse process, where they 

 meet ; the depressions between and on each side of these ridges are deep : 

 the third ridge extending from the anterior part of the base of the neura- 

 pophysis to the anterior oblique process stands out in nearly as bold relief 

 as those which support the transverse process. 



The articular surfaces on the oblique processes are bounded by a regular 

 convex free margin ; their long diameter is 1 inch 10 lines, their short dia- 

 meter 9 lines ; they are nearly flat : the anterior ones look inwards and up- 

 wards ; the posterior downwards and outwards. 



* Loc. cit., p. 308. t Ossem. Foss. v. pi. ix. fig. 3 and 10. 



