100 REPORT— 1841. 



face ; the posterior confluent pair, forming a triangular prominent surface, 

 inclining obliquely forwards, and with its apex notched by the termination of 

 the inferior sulcus. 



There are several posterior caudal vertebrae of the Cetiosauriis brevis in the 

 Mantellian Collection,which closely correspond with those just described from 

 the Hastings beds; four of these vertebrae give the following dimensions : — 



Nos. 2112. 2142. 2153. 



Antero-posterior diameter of centrum ^ . 

 Transverse diameter of its articular end 

 Vertical diameter of its articular end . . 

 Vertical diameter at middle of the centrum 



The vertebrae figured in the ' Illustrations of the Geology of Sussex,' pi. ix. 

 fig. 8, and pi. x. fig. 1 , are posterior caudal vertebrae of the Cetiosaurus brevis. 



Cetiosaurus brachyurus — A dorsal and a caudal vertebra from the Weal- 

 den formation at Tetham, which agree in essential characters with the Cetio- 

 saurus, and differ from those of Streptospondylvs, Megalosaurus, Iguanodon, 

 Hylceosmirus, Poikilopleuron, and the Crocodilian vertebrae of the Wealden, 

 offer at the same time proportions which forbid their reference to the Cetio- 

 sauri brevis, medius and longus, and indicate a species distinguished by a 

 shorter tail. 



The dorsal vertebra (No. ~, Mantellian Collection) presents a subcircular 

 centrum, with the neui-apophyses anchylosed, but broken off; they are shorter 

 than the centrum, and leave eight lines of its hind part uncovered. The 

 anterior articular surface of the body is slightly convex at the upper, and con- 

 cave at the under half : the posterior surface is uniformly concave : the body 

 is constricted at the middle, but in a less degree than in the Cetiosaurus brevis, 

 so that it is less deeply concave lengtliAvise : it is as convex transversely : a 

 slightly-raised obtuse ridge separates two shallow sulci at the under surface 

 of the vertebra. 



The caudal vertebra (No. ^) Mantellian Collection) presents a shallow 

 and rather oblique sulcus along the lower surface. The hagmapophysial ar- 

 ticulations are most marked at the posterior part of this surface. The sides 

 of the centrum are less concave longitudinally than in the dorsal vertebra ; 

 there is a vascular perforation on each : the articular ends of the body agree 

 with those of the dorsal vertebrae. The following are dimensions of the pre- 

 ceding vertebrae : — Dorsal. Caudal. 



In. Lin. In. Lin. 



Antero-posterior diameter of body ... 3 2 9 



Vertical diameter of articular end ... 4 3 3 10 



Transverse diameter of articular end . . 4 6 3 7 



These vertebrae closely corresponded in texture and character of the ex- 

 ternal surface*. 



Cetiosaurus medius. — The remains of this Reptile have hitherto been dis- 

 covered only in the oolitic strata below the Wealden. They appear to have 

 been first noticed in a letter from John Kingdon, Esq., read at the meeting 

 of the Geological Society held June 3rd, 1825, in which "he mentions the 

 situation in which certain bones of a very large size, appearing to have be- 

 longed to a Avhale and a crocodile, were lately found completely imbedded 

 in the oolite quarries (lower oolite), about a mile from Chipping Norton, 

 near Chapel House." It is principally on these bones, with others subse- 



* They are probably the bones alluded to in the Note at p. 221 of Dr. Mantell's ' Geology 

 of the South-east of Enrfand.' 



