METRI0EHYNCI1US. 



171 



small paddle-like structure much as in Geosaurus. The shoulder-girdle is formed 

 by the scapula and coracoid only. 



The scapula (sc.) is a slender flattened bone, widening out a little at its upper 

 end, which terminates in a smooth convex surface. At the lower end the expansion is 

 greater and the posterior side much thickened, the thickened portion bearing two 

 surfaces. Of these, one is roughened and triangular in outline for union with the 

 coracoid ; this extends nearly the whole width of the end of the bone. The other facet 

 is smooth and looks outwards, downwards, and backwards, forming the upper part of 

 the glenoid cavity for the humerus. In front of the surface for the coracoid, the bone 

 is produced into a blunt angle. 



Text-fig. 69. 



Shoulder-girdle and humerus of Metriorhynchus : A, right half of shoulder-girdle of If. superciliosum 

 (R. 2051, | nat. size) ; B, right half of shoulder-girdle with the humerus of M. lave (~R. 3014, 

 | nat. size). 



c,r., coracoid ; d.c, deltoid crest ; /., coracoid foramen ; r/l.f., glenoid fossa ; h., head of humerus ; 



n., notch on coracoid ; sc, scapula. 



The coracoid (cor.) is considerably larger than the scapula; it is a strongly com- 

 pressed bone, expanding to a fan-like shape at each end. The upper end is thickened 

 posteriorly, the thickened portion bearing on its upper edge the surface for union with 

 the scapula, while, looking backwards, there is a large oval, slightly concave surface 

 which forms the lower two-thirds of the glenoid cavity. In front of this the bone is 

 perforated by a large coracoid foramen (text-fig. 69, A), which, however, in some cases 

 may become a deep notch (text-fig. 69, B). Sometimes this is the result of the 

 breaking away of the border of the bone, but in others the notch has clearly never 

 been closed (text-fig. 70, B). The neck of the bone is only about as wide as the upper 



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