SAUROPTEKYGIA 213 



The clavicle, which is an exogenous process in Plesiosaurus, 

 is here united by a strong oblique suture to the scapula. It 

 expands into, or sends off from its outer part, a broad, flat, obtuse 

 process, near the suture ; then contracts and bends inwards to 

 the episternum, to winch it is articulated also by suture. 



The coracoid (fig. 69, 52) sends forward a broad and short 

 flattened process, separated by a narrow notch from the 

 scapular part of its head ; it then contracts and soon expands 

 into a broad, flat, sub-triangular plate, the broad and straight 

 border of which articulates with that of the opposite coracoid. 

 A wide unossified interval separates the coracoid from the 

 episternum. The ossification of the coracoid in the direction 

 of this interval gives the peculiar longitudinal or fore-and-aft 

 extent to those bones in the Plesiosaur, in which they unite 

 with the episternum. 



The pelvic arch presents a closer correspondence with that 

 in the Plesiosaurus (fig. 71 ). The ischium (fig. 69, 63), con- 

 tracting beyond its articular head, there expands into a flat 

 subtriangular plate. The pubis (fig. 69, 64) is a subcircular 

 flat bone, with a notch near the articular end. 



The bones of the limbs, although evidently those of fins 

 or paddle-shaped extremities, are better developed than in 

 Plesiosauncs, and more resemble the corresponding bones in 

 the turtle (Chelones). The tuberosities or processes for muscu- 

 lar attachment near the head of the humerus (omitted in the 

 diagram) are better marked, especially that on the concave 

 side of the shaft ; the distal end is thicker and less expanded. 

 The whole bone is more curved than in any Plesiosauri. The 

 femur (fig. 69, 65) is relatively longer and less expanded at its 

 distal end. The bones of the fore arm, like those of the leg 

 (ib. 66 and 67), are longer than in Plesiosaurus. The articular 

 surfaces present the foramina with raised borders, which 

 characterize those in Plesiosavri, and which indicate the fibro- 

 cartilaginous nature of the joints. 



