4 6 



Field Columbian Museum — Geology, Vol. II. 



the emargination behind represents a distinct foramen in the com- 

 pleted girdle — the interclavicular foramen, of which the only mention 

 hitherto that I can find is tjy Seeley (Proc. Roy. Soc. Lond. li, p. 140), 

 whose figures I reproduce here. 



In PI. XV is shown the articulated pectoral girdle from below. 

 and in PI. XIV, the same is shown in front view. As a whole, 

 the girdle forms a rather deep trough, with the dorsal rami of the 

 scapula directed upward and somewhat outward. Its exact position 

 in relation to the ribs is difficult to state, but I do not think that the 

 position given in the restoration can be far wrong. The slight 



Fig. 11. 



Sc apuloc lavicular girdle of PUsiosaurtts nuidgci from above; the missing parts restored in 



dotted lines. Ic, episternum; <l .. clavicle; fc., scapula, - co., epicoracoid process. 



degree of curvature of the ribs in the pectoral region must have left a 

 rather angular margin to the thorax on either side, filled in, in part at 

 least, by the cartilaginous continuation of the thoracic ribs, which 

 the preserved ends plainly show were present. The upper surface of 

 the girdle was not hollowed much, if any, longitudinally, so that the 

 base of the neck must have been in life quite deep. 



An examination of the under surface of the girdle, as shown in 

 PI. -XV, furnishes, I think, convincing proof that the space between 

 the scapulae, epicoracoid process and the elliptical lines on the ven- 

 tral surface of the episternum was filled in in life by cartilage, join- 

 ing the coracoid and scapula and covering the squamous portion of 

 the episternum, but leaving the interclavicular foramen free. Ossifi- 



