118 REPORT — 1841. 



terrupted and full convex curve commencing at the angle dividing it from the 

 scapular articular surface ; but it is separated by a concavity or emargination 

 from tiie articular surface for the humerus. It is perforated by a moderate 

 sized elliptical canal, about two inches from the humeral articulation, and in 

 this respect resembles the same bone in the Iguana, Monitors and Lizards, 

 and differs from the Scinks and Chameleons. The antero-posterior extent of 

 the coracoid in the connected portion of skeleton is eight inches ; its trans- 

 verse diameter five inches. 



A humerus, and a phalangeal bone found with the scapula, near Bolney, 

 are figured by Dr. Mantell in the Memoir of 184'1. 



Tteth of the Hylccosaur ? — With regard to the Hylceosaurus Dr. Mantell ob- 

 serves, in his latest geological work, " the teeth are unknown ; but in the quar- 

 ries where the bones of that reptile were discovered, I have found teeth of a 

 very peculiar form, which appear to have belonged to a reptile, and are en- 

 tirely distinct from those of the Megalosaurus, Iffuanodon,Crocodi\e and Ple- 

 siosaurus, whose remains occur in the Tilgate strata*." The form and struc- 

 ture of these teeth, which will be presently described, deviate too much from 

 those of the Crocodilian family to make at all probable a reference of them 

 to the genera Poikilopleuron, Streptospondylus, or Cetiosaur, which are much 

 more closely allied to the Crocodilians than is the Hylseosaur. In the 'Geology 

 of the South-east of England,' Dr. Mantell attributes these teeth, on the author- 

 ity of M.Boue, to the Cylindricodon, a name by which Dr. Jager distinguishes 

 one of the species of his genus ^Phyiosaurus.' I have been favoured by Dr. Jager 

 with one of the bodies supposed to be the teeth of the Cylindricodon of the 

 Wirtemberg Keuper, but it is merely the cast of a cylindrical cavity, consist- 

 ing entirely of that mineral substance, without a trace of dental structure. 

 The difference of form between the Wealden teeth now under consideration, 

 and those on which the Phytosaurus cylindricodon of Jager was founded, is 

 pointed out in detail in my Odontography, and has been likewise appreciated 

 by the estimable Palaeontologist, M. Fischer de Waldheim, by whom their re- 

 semblance to certain Saurian teeth from the Ural Mountains, belonging to the 

 genus Rhopalodon\, is indicated. From these teeth, however, the presumed 

 Hyteosaurian teeth differ in having thick and flat instead of serrated coronal 

 margins. The following is Dr. Mantell's original description of the teeth in 

 question : — 



" These teeth are about an inch and a quarter in length, and commence 

 with a subcylindrical shank, which gradually enlarges into a kind of shoulder, 

 terminating in an obtuse angular apex, the margins of which are more or less 

 worn, as if the teeth had been placed alternately so as to meet at their edges, 

 as in pi. ii. fig. 3. They are obscurely striated longitudinally, and have a 

 thick coat of enamel : the crown of the tooth is solid, but the shank is more 

 or less hollow. All the specimens appear as if they had been broken off" close 

 to the jaw; but they may have been separated by necrosis occasioned by the 

 pressure of the supplementary teeth J." 



The following is the result of a microscopical examination of these teeth. 

 The tooth consists of a body of dentine covered by a thick coating of clear 

 structureless enamel, and surrounding a small central column of true bone, 

 consisting of the ossified remains of the pulp, which presents the usual cha- 

 racters of the texture of the bone in the higher reptiles. The dentine differs, 

 like that of existing Lacertians, from the dentine of the Iguanodon in the en- 

 tire absence of the numerous medullary canals which form so striking a cha- 



* Wonders of Geology, vol. i. p. 403. 



•f- Lettre siir le Rhopalndoyi, Moscow, Svo, 1841. 



X Geology of the South-east of England, p. 293. 



