PICEOCLEIDUS BELOCLIS. 143 



margins of the interclavicle are sharp, thin, and perfectly ossified, like its median crest. 

 It is therefore probable that the clavicles were either loosely articulated to its margin, 

 or extended between the interclavicle and scapvJa." 



The interclavicle {i.cl.) thus described is shown on PI. VIT. figs. 2, 2 a. In section it 

 is nearly triangular, and the ventral angle no doubt fitted between the divergent anterior 

 ends of the ventral rami of the scapulae; possibly, however, these were already united 

 by cartilage, so that the interclavicle would be completely shut in below. The film- 

 like patches of bone are probably remnants of the disappearing clavicles, as Seeley 

 suggests: m Murcenosaurus flatycUs (see PI. VI. fig. 3) a somewhat similar condition is 

 found, though the reduction has not been carried nearly so far. 



The scapul(B (se., PI. VII. fig. 2) are similar to those of Tricleidus, except that the 

 ventral I'ami {v.sc.) are relatively smaller. Their sutural union in the middle line is 

 wide and strong, and posteriorly is continuous with the median suture of the coracoids ; 

 anteriorly it is limited by a deep notch, and in front of this is the cleft occupied by the 

 interclavicle. The dorsal ramus [d.sc.) is large, but neither it nor the posterior part of 

 the bone presents any important peculiarities. 



The coracoids {cor., PL VII. fig. 2j are smaller, and especially shorter, in proportion 

 to the girdle as a whole than in the other genera. As usual in the group, they 

 unite in a long median suture which extends forwards to the scapulas, completely 

 dividing the coraco-scapular openings. Between the glenoid cavities [gl.) the bones 

 are much thickened, particularly towards the middle line, the symphysis here being 

 very deep. Posteriorly the bones are thin. The surface for union with the head of 

 the scapula is triangular and makes an angle of 120° with the glenoid surface, which 

 with the glenoid surface of the scapula makes a deep oval fossa for the articulation of 

 the humerus. Behind the glenoid cavity the lateral border of the coracoid is deeply- 

 concave. Posteriorly it runs out into a well-developed postero-lateral process, from 

 which the concave posterior border runs inwards and backwards to the pointed internal 

 process, which is separated from its fellow in the middle line by a V-shaped notch. 



The humerus (PI. VII. fig. 2 h) of the type specimen is a comparatively short stout bone; 

 it is almost completely ossified, the head being strongly convex, owing to the extension 

 of ossification into the cartilaginous cap. The surface of the head (A.) is still much rough- 

 ened, and bears a number of small prominences, perforated at their summit for the 

 passage of nutritive ve.ssels. This roughened surface is continued on to the upper end 

 of the strong tuberosity (l-P-), the form of which is shown in the figure. The outer 

 surface of the process near its upper edge is raised into a series of strong ridges parallel 

 with the long axis of the bone. The ventral surface of the upper end of the shaft is 

 much roughened, and raised into slight prominences for the attachment of muscles. 

 In section the outline of the shaft is a depressed oval, the long axis being in the same 

 direction as the distal expansion. This is not very greatly developed, and is mainly 



