152 REPORT — 1811. 



proximal end, is nearly entire; it terminates by an irregular convex border, 

 not thinned off to an edge, but adapted to the formation of a joint, and to the 

 attachment of cartilage. The exposed surface of the expanded head is con- 

 cave from side to side., somev. hat resembling the expanded and bent pubic 

 plate in lizards. The opposite extremity is broken across ; it shows the com- 

 mencement of a slight longitudinal ri(lge near its middle part. This bone 

 bears most resemblance to a humerus, but I am at present unable to deter- 

 mine it unequivocally. If compared v.ith the left pubis of Lacertians, the 

 entire and bent extremity corresponds with the median portion of that bone ; 

 but the middle part or stem is much longer in the fossil, and the broken end, 

 which would agree with the acetabular end of the pubis, is too thin to have 

 entered into the formation of such a cavity in the fossil ; it likewise wants the 

 perforation which characterizes the pubis in lizards. The same thinness and 

 imperforate condition of the fractured end oppose the comjjarison of the pre- 

 sent bone with the coracoid of the Crocodile. 



In. Lin. 



Length of this bone as far as complete 19 



Breadth of middle 3 



Breadth of entire expanded extremity 10 



In the slab containing the above-described bones, there are other fragments 

 of bone, but too small and imperfect for profitable description. Those of 

 which I have endeavoured to make the form and analogies intelligible, though 

 evidently peculiar, as might be expected in a Saurian with so strange a head, 

 and perhaps with a hind-toe directed backwards as in birds, may be regarded 

 as, most probably, constituents of a strong and well-developed pectoral arch, 

 and a humerus ; and they indubitably indicate a mechanism for locomotion 

 on land, which would well agree with that of the animal that has left the im- 

 pressions of its footsteps upon the same sandstone. 



Radius and Ulna. — Another piece of coarse-grained sandstone from the 

 same quarry contains a series of seven or eight vertebrfe in a very fragmentary 

 state, also two or three ribs, rather more slender and not so distinctly grooved 

 as in the fine-grained slab, and the proximal extremities of two long bones, 

 which may be best compared with the radius and ulna. The shaft of the 

 radius is more slender than that of the ulna ; one side is flat, the other con- 

 vex ; it expands and assumes a subtrihedral figure, by the development of a 

 slight longitudinal ridge ; its proximal end is conipi-Cfscd and more suddenly 

 expanded ; its breadth is 2\ lines, that of the shaft of the bone is 1 line. The 

 impression, partly broken away in the stone, indicates the greater expansion 

 of the distal end of this bone, with a length of 1 inch 3 lines. The proximal 

 end of the ulna has a distinct trihedral figure, and the expanded extremity is 

 produced backwards, so as to indicate the olecranon; the breadth of the head 

 is 4 lines, that of the middle of the shaft is 2^ lines. There is a portion of a 

 broad and flat bone in this piece which may have belonged to the scapular 

 arch. 



Ilium. — In another piece of stone, with the other portion of the same chain 

 of five vcrtebrcB, there is a broad and flat bone, apparently terminating in a 

 long narroAv process at one end, which may be an ilium ; its length is indi- 

 cated to be at least 1 incii 7 lines. 



Femora. — A thin piece of burr or coarse-grained sandstone contains the 

 articular end of a broad and flat bone, in which the raised oblong surface of 

 the joint is divided by a smooth channel, and may be compared with the co- 

 tyloid portion of the ilium ; the same piece of stone contains the shafts of two 

 long bones, most probably femora. The length of the most perfect of these 

 is 2 inches, and this does not include the distal end ; the diameter of the 



