274 



The specimen represented in Fig. 10 I suppose to be a fibula, though it may 

 be an ulna. It is a broad bone, almost as wide as the femur, but not so long. 

 Its flatness lias been somewhat increased by pressure. The upper extremity 

 presents a wide, lenticular, uneven, convex, and roughened surface for carti- 

 laginous union with the femur. The lower extremity presents a similar sur- 

 face, but wider and of less depth or thickness. 



The measurements of the specimen are as follows: 



Lines. 



Length of fibula 60 



Width of upper extremity 54 



Thickness of upper extremity 21 



Width of lower extremity, partly estimated 65 



Thickness of lower extremity 17 



Width of shaft near middle 38 



Thickness of shaft 13 



The supposed tibia, represented in Fig. 11, is a much smaller bone than 

 the fibula. It is clavate, with the lower extremity the more expanded and 

 thinner. The upper part of the shaft is compressed cylindroid, and becomes 

 wider and more compressed below. The upper extremity presents a trian- 

 gularly oval, slightly convex, articular surface, rugged as in the other bones. 

 The lower articular surface is transversely convex and widely lenticular. 



The measurements of the specimen are as follows : 



Lines. 



Length of the tibia 45 



Width of upper extremity - 21 



Thickness of upper extremity 14 



Width of lower extremity 34 



Thickness of lower extremity 11 



Width of narrowest part of shaft . . 12 



Thickness of narrowest part of shaft .... » 10 



Tylosaueus peoeigee. 



Dr. Sternberg's collection of Kansas Cretaceous fossils, preserved in the 

 Museum of the Smithsonian Institution, contains specimens pertaining to 

 several individuals of -a large Mosasaurus-like reptile, approximating in size 

 the Maestricht Monitor of Europe, and the Mosasaurus Mitchelli. of New 

 Jersey. The specimens appear to pertain to the same animal as that de- 

 scribed by Professor Cope under the names of Macrosaurus and Liodon pro- 

 riger, and afterward, as in the case of the former species, referred to another 

 genus by Professor Marsh, under the name of Rhinosaurus, then by Professor 



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