SAUROPTERYGIA. 233 



broad, flat, sub-triangular plate, the broad and straight border 

 of which articulates with that of the opposite coracoid. A 

 wide unosshied interval separates the coracoid from the epi- 

 sternum. 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 episternuni. 



The pelvic arch presents a closer correspondence with that 

 in the Plesiosaurus (fig. 93). The ischium (fig. 90, 63), contract- 

 ing beyond its articular head, there expands into a flat sub- 

 triangular plate. The pubis (ib., 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 Plesio- 

 saurus, and more resemble the corresponding bones hi the 

 turtles (Chelones). The tuberosities or processes for muscular 

 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. 90, 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 Plesiosauri, and which indicate the fibro- 

 cartilaginous nature of the joints. 



There is a ligamentous or unossified space at the back part 

 of both carpus and tarsus (fig. 90, 68). At present there is 

 evidence of but four digits in both the fore and hind paddles 

 of Xotlwsaurus : the metapodial and phalangeal bones are of 

 the elongate flattened simple form, characteristic of supports 

 of a tegumentary fin. 



One species of Kotliosaurus {N. Schinvperi, Yon. M.) is from 

 the lower division of the trias, called "gres bigarre," of Soulz- 



