CIMOLIASATTRTJS. 25 



at its root for an elastic ligament. The greater portion of a remaining posterior 

 articular process indicates this to be of smaU size, and it has its facet directed down- 

 ward and outward. 



The side of the body is extended into a large process excavated to its base into 

 a vertical, ear-shaped, concave, costal pit, bounded by an elevated, acute margin. 

 The vertical diameter of the pit is equal to two-thirds that of the body, and its 

 transverse diameter equal to half the length of the latter. The upper extremity 

 of the pit is formed by a trilateral process projecting outwardly from the root of 

 the vertebral arch, and is separated from the rest of the pit by a deep, crescentoid, 

 transverse fissure, remaining as part of the suture through which the arch is united 

 with the body of the vertebra. 



The measurements of this vertebra are as follows : — 



Lines. 



Length of the body . . ' 31 



Breadth of the articular extremities 43 



Height of the articular extremities ......... 33 



Breadth of costal pits 15 



Height of costal pits 2t 



Breadth of spinal canal . . . . . . . . . . .11 



Height of spinal canal 12 



The carpal bone, represented in Figs. 13, 14, Plate IV, resembles those of Plesio- 

 saurus. It is a thick hexahedral tablet, with the broad surfaces concave and rugged. 

 The borders are half the width of the broad surfaces, and present parallel rows of 

 nutritious foramina. The bone measures in its greater breadth thirty lines, in its 

 lesser twenty lines, and its thickness ranges between twelve and sixteen lines. 



The metacarpal bones, represented in Figs. 15, 16, 17, likewise resemble those 

 of Plesiosaurus. They are quadrilateral columnar bones, with the sides concave 

 longitudinally. The extremities are quadrate in outline, and their surfaces exhibit 

 parallel rows of nutritious foramina. 



The phalanx, represented in Fig. 18, also resembles those of Plesiosaurus. It 

 is a shghtly compressed cylindrical column, expanding from the middle towards 

 both extremities. 



The carpal, metacarpal, and phalangeal bones indicate that they were articulated 

 by cartilage, and together with the other bones of the extremity formed a paddle 

 like those of Plesiosaurus. 



It is not improbable that I may have included, in the account of Discosaurus 

 vetustus, the remains of more than one species, but the material at command 

 appeared to me insufficient to justify a separation. 



CIiUOIilASAlJKVS. 



Cimoliasaurus mag^nus. 



CimoUasaurus magnus, Leidy, Proc. Acad. Nat. Sci. Phila. 1851, 325 ; 1854, 72, pi. ii, figs. 4, 5, 6. 



Vertebrae differing from any of those described in the preceding pages, and 

 belonging to a huge Saurian, are frequently found in the Green-sand deposits of 



4 Maroh, 1865. 



