270 



extending to the commencement of* the distal expansion of the shaft. It 

 resembles nearly' the corresponding portion of the humerus of the snapper 

 completely flattened, or a miniature of that of Atlantochelys in the saftne con- 

 dition. The greater tuberosity appears to spring from above the tpp of the 

 head externally, so that its upper anterior border looks like an extension of 

 the articular surface of the latter. A strong muscular impression is situated 

 upon the inner fore part of the shaft. The lesser tuberosity 'projects poste- 

 riorly, and ends in a thick, roughened, convex surface. 



The breadth of the specimen between the two tuberosities obliquely meas- 

 ures 33 lines ; the breadth of the shaft, where narrowest, is 10 lines. 



Fig. 18, represents a complete femur, apparently from the same individual 

 as the former. As in the snapper and Trionyx, it is of proportionately less 

 breadth than the humerus. It is apparently much flattened by pressure, so 

 as to differ considerably from its exact original form. The trochanters appear 

 relatively to have been as well developed as in the snapper, and the distal 

 articulation may be supposed to have had nearly the same form. 



The length of the femur is 5^ inches. The breadth of the upper ex- 

 tremity is 20 lines, of the lower extremity 16* lines, and of the middle of 

 the shaft 7 lines. 



Several additional bones accompanying the former appear to belong to the 

 shoulder of the same animal. 



Fig. 19, represents what appears to be a portion of the left scapula with its 

 upper end and the prse-coracoid prolongation broken ^^ay. The specimen 

 appears distorted and flattened from its normal condition as the result of 

 pressure. 



Fig. 20, represents what appears to be a portion of the coracoid bone of 

 the same side, also somew r hat distorted by pressure. 



Fig. 21, represents another bone-fragment, apparently from the same indi- 

 vidual, which I cannot determine to my own satisfaction. Like the other 

 specimens, it appears flattened from its normal condition. 



Order Mosasauria. 



Large, extinct, marine saurians, most nearly constructed as in Lacertilians, 

 but having limbs constructed as paddles for swimming. The relations of these 

 reptiles with the serpents, as suggested by Professor Cope, in his Synopsis of 

 the Extinct Batrachia, Reptilia, &c, have been much reduced by the subse- 



