1855.] OWEN — PRORASTOMUS SIRENOIDES. 541 



P.S. — Since the above was written, Capt. Collinson transmitted 

 to me an instructive collection of rock-specimens, collected during 

 his survey. Most of them show the great prevalence of crystalline 

 rocks along the north coast of America. 



2. On the Remains of Dicynodon tigriceps, Owen, from 

 South Africa. By Professor Owen, F.R.S., F.G.S. 



(This paper will be published in full in the 4th part of the 7th vol. of the 



" Transactions.") 



[Abstract.] 



In this communication the author described certain vertebrae, the 

 sacrum, the pectoral and pelvic arches, and one of the long bones 

 of the extremities, of a large-sized Dicynodon, probably referable to 

 the species D. tigriceps, the cranium ojp which Prof. Owen described 

 in a previous paper. (See above, p. 532.) 



These fossils form part of the extensive collection of Saurian 

 remains collected and forwarded to England some years since by 

 A. G. Bain, Esq. 



From the indications aiforded by the above-mentioned bones of 

 the trunk and limbs, the author concluded that, although the Dicy- 

 nodon was amphibious, and could doubtlessly swim well, it possessed 

 limbs capable of active movements on land, and probably adapted to 

 other uses. 



3. On the Fossil Skull of a Mammal (Prorastomus sire- 

 NOiDES, Owen), from the Island of Jamaica. By Professor 

 Owen, F.R.S., F.G.S. 



[Plate XV.] 



The subject of the present notice was submitted to me by Henry 

 H. Shirley, Esq. : it was found in Jamaica in a river-course which 

 is composed of red conglomerate and sandstone, overlaid by lime- 

 stone, differing from the general tertiary carious limestone of the 

 Island and beneath it : the locality is near ^'Freeman's Hall Estate, 

 between the Parishes of St. Elizabeth and Trelawney, at that central 

 high ground or ridge which forms, as it were, the back-bone of the 

 Island." (MS. note sent with the specimen.) 



The fossil was imbedded in a nodule of hard calcareous shelly rock, 

 which had been broken in pieces : three of the largest of these con- 

 tain portions of a skull, which, on being partially cleared of the 

 matrix, exhibited the following characters : — 



An occipital portion with two condyles, and a tolerably capacious 

 brain-case, showing its mammalian nature (PI. XV. fig. 1) ; and a 

 facial portion, figs. 2 & 3, with the fore part of the lower jaw, fig. 4, 

 indicative of an affinity to the Manatee, but with well-marked cha- 

 racters distinctive from any known existing member of the Order 

 Sirenia. 



2 o 2 



