FATTXA OF THE GOSAT7 FORMATION. 



679 



pressed than the posterior margin. There is an indication of a ridge 

 towards the proximal end, similar to that on the opposite side of 

 the bone; and between these ridges, which are 13 millim. apart, 

 the proximal end of the bone is concave from side to side. The bone 

 does not greatly thicken at the proximal end, the greatest thickness 

 towards the anterior border is 6 millim. There is a general re- 

 semblance in character to the scapula attributed by Professor Owen 

 to Iguanoclon Mantelli (Pal. Soc. 1854, pi. xiv. fig. 1) ; but in this 

 form the blade is not so constricted, and it may be doubted whether 

 the anterior process there so marked attained any corresponding de- 

 velopment in this fossil ; nor is the resemblance closer to Scelido- 

 saurus ; and, indeed, in the straightness of its posterior margin the 

 bone rather suggests the scapula of an Ichthyosaurus, in which, how- 

 ever, the straight margin is anterior. 



Humerus. 



The bone which Biinzel identifies as belonging to the right side 

 of the body seems to me to be referable to the left side. The 

 reason for this determination is that the articular head of the bone 

 is on the right side, as proved by the thickening, and the radial 

 crest On the left side. Like most of the other specimens, this is im- 

 perfect at both the articular ends, though enough remains to convey 

 an idea of the form and length of the bone before it was mutilated. 

 The shaft, which is greatly expanded proximally, is 5 centim. long. 

 The distal end has the superior and inferior surfaces parallel ; and 

 the bone is 8 millim. thick and nearly 12 millim. wide, more 

 rounded on the anterior than on the posterior border. From the 

 superior outer border a faint rounded ridge extends up the shaft 

 towards the middle of the articular head ; and an impression occurs 

 in its upper half which appears to be muscular. The width of the 

 bone at the proximal end, just above this ridge, is 22 millim. In- 

 ternal to the ridge the bone is compressed, so as to contribute to 

 form the articular head. External to the ridge it is transversely 

 expanded, somewhat flattened, and marked with strong longitudinal 

 grooves at the outer extremity of the radial border. The radial 

 border is more concave than the ulnar border. The thickness of the 

 radial expansion is about 6 millim., but diminishes proximally. 

 The thickness of the base of the proximal articulation where frac- 

 tured is about 9 millim. The inferior surface is regularly concave 

 from side to side at the proximal end, and convex in length, cor- 

 responding to the transverse convexity and longitudinal concavity 

 of the superior surface. The shaft where most constricted, in its 

 lower third, is less than 1 centim. wide, while its thickness steadily 

 diminishes from the distal end to the radial margin at the proximal 

 end. This bone possesses none of the typical characters of a lizard- 

 humerus, but all those which are usually found in Dinosaurs, though 

 I am unable to name any genus in which the form of this bone is 

 so closely paralleled as to suggest generic identity or even affinity. 

 The distal fracture, which is transverse, is so irregular as to suggest 

 an epiplrysial surface from which the epiphysis has come away. 



