ON THE FAUNA AND FLORA OF THE TRTAS OF THE BRITISH ISLES. 29? 



to the front part of the glenoid articulation for the humerus. The 

 scapula is still represented only by the specimen described by Owen 

 (l,pl. vi., lig. 8), and by an imperfect example in .S. No. i. It is expanded 

 and shaped nearly as in Sphenodon, but somewhat shorter and broader, 

 and, like the coracoid, more extensively ossified than the corresponding 

 element in the existing genus under comparison. The ' moderately long 

 trihedral process given off from the convex margin near the articular end ' 

 of this bone, described and figured by Owen, does not exist, but depends 

 on the misinterpretation of a fragmentary part of the fossil. There is 

 very little space for a sternum, the abdominal ribs approaching the inter- 

 clavical more clo.sely than in Si^henodon. The humerus (Plate II., figs. 2, .3), 

 already noticed by Owen (1, 3) and Huxley (4), is relatively shorter and 

 bi-oader than in Sj^henodon but twisted to the same extent. AH the known 

 .specimens are incomplete, but two are sufiiciently well pi-eserved at the 

 lower end to show that there is no epicondylar foramen. The radius and 

 ulna are not quite so long as the humerus, and are better shown in the 

 original of Plate II., fig. 2, than in any specimen hitherto described. The 

 ulna (m) is the stouter bone, with a marked triangular expansion at the 

 upper end, but a smaller olecranon process than in Sphenodon. The 

 radius (r), which is only slightly expanded at each end, extends further 

 down into the carpal region than the ulna. The carpus seems to have 

 been less ossified than in the existing Sphenodon, and is represented chiefly 

 by a vacant space in the fossil. In Plate II., fig. 2, an obscure trace of an 

 intermedium is seen, separating the lower ends of the radius and ulna 

 less widely than in Sphenodon. There are also traces of the ossified ulnare 

 and carpalia Nos. 2 and 4. Indications of the same ossified carpal 

 elements ai-e also observable in S. No. 4. The five digits of the fore foot 

 are comparatively stout, and the fifth is I'elatively much shorter than in 

 Sphenodon. The phalangeal formula is clearly 2, 3, 4, 5, 3, and the 

 terminal phalanges must have formed slender pointed claws. 



Hind Limb. — The hind limb is larger than the fore limb, its relative 

 proportions being indicated in the accompanying text-figure. As shown 

 in the imperfect skeleton described by Huxley (4 pi. xxvii., fig. 4), the 

 pelvis is characterised by the great expansion of the ischia and the conse- 

 quent reduction in .size of the obturator foramen. These bones are only 

 represented by impressions in the specimen mentioned, and they are 

 evidently crushed, so that their precise form and relations are uncertain. 

 The ilium is incompletely known, but a fragmentary specimen is noticed 

 by Owen (1, pi. vi., fig. 10) in a fossil which I have not found in the 

 Shrewsbury collection. The bone is also partly exhibited in S. No. 5, in 

 which appearances suggest that the ilium met the ischium and pubis in 

 a closed acetabulum. The femur, tibia, and fibula are .shown by B.M. 

 No. R. 1239 to have had an internal cavity, but they are not well- 

 preserved in any known specimen. The femur is sigmoidally bent to about 

 the same extent as that of a crocodile, and its length somewhat exceeds 

 that of the tibia and fibula. The precise shape of the tibia is unknown, 

 but the fibula is equally expanded at each end, and as widely separated 

 from the tibia as in Sphenodon. The tarsus must have been considerably 

 ossified, but its elements are confused in the fossils, and their identification 

 is uncertain. The foot is only known by the two incomj>lete specimens 

 despribed by Huxley (4, pi. xxvii., figs. 4, 5). It is long and narrow, with 

 the five toes ending in small pointed claws ; but it is relatively shorter 

 than in Sphenodon. Both the metatarsals and the phalanges are relatively 



