226 DR. R. -W. SHUFELDT ON [Apr. 1, 



the bone, as in tlie case of the coracoid, being transversely flattened. 

 Its antero-ventral end fuses with the coracoid, while its postero- 

 ventral end goes to help form the dorso-superior part of the glenoid 

 cavity. Its antero-superior angle articulates with the outer end of 

 the corresponding clavicle, and its dorsal border articulates, for its 

 entire length, with the superimposed suprascapula. 



The expanded dorsal part of the scapula is harmoniously extended 

 by the still more dilated semi-osseous suprascapula. The dorsal 

 border of this element of the girdle is markedly convex, the mid- 

 point of its arc almost reaching to the transverse processes of the 

 vertebrae of the spine above it. In situ, it is seen to be a thin 

 plate resting upon the last four cervical ribs by its mesial flat surface, 

 being connected with the rest of the girdle in the manner we have 

 described. 



The Interclavicle (episternum) is rej)resented by an azygos bony 

 bar, which is somewhat dilated and vertically compressed behind, 

 while it is small and tapering in front, at which latter point it stands 

 between the mesial ends of the clavicles, being slightly dorsad to them. 

 Posteriorly its dilated extremity is attached to the ventral surface 

 of the antero-mesial angle of the sternum, the union being through 

 the medium of firm ligament. 



Either clavicle is represented l)v a slender, subcompressed bone 

 articulating in a manner already indicated above. When seen in 

 situ it at first passes from its articulation with the interclavicle 

 outwards. Near the middle point of its shaft it bends at a gentle 

 angle upwards, and from thence goes to its facet, found at the 

 antero-dorsal angle of the corresponding scapula. The mesial end 

 of the clavicle is but slightly larger than its outer extremity, and the 

 form of the bone thus aff'ords a good classificatory character. Upon 

 close examination, in some specimens, it may be discovered that its 

 extreme outer tip may come into contact with the suprascapula at 

 its antero-ventral angle. 



The Pectoral Limb. — Averaging some 3'4 centimetres in length, 

 the humerus presents a rather short subcylindrical sliaft, with 

 scarcely any curvature. Its extremities are markedly expanded, the 

 imaginary planes in which they He intersecting each other at an 

 angle of about Sf) degrees. The head of the humerus is an elongated 

 facet, and throughout life the sutural trace showing where this is 

 united with the rest of the bone is distinctly visible. To the radial 

 side of this is a bony crest for muscular insertion, having a form much 

 as we see it in ordinary existing birds. This crest is turned ulnad 

 so as to make an angle with the rest of the head of the bone, which is 

 also similar to what we find in this last-mentioned class. Distally, 

 there is an ulnar and radial tubercle, condylar sui faces for articulation 

 Avith the bones of the antebrachium. In their form these also 

 remind us of the corresponding structures in birds, though here in 

 this Lizard the epiphysial sutural trace is visible during the life of 

 the individual. The epiphysis in question includes the entire 

 articular portion. Above the radial tubercle, the side of the expanded 

 end of the shaft develops a moderately prominent ridge several 



