NO. IfiOO. 



OSTEOLOGY OF CAMPTOSAURUS—GILMORE. 



261 



trastiiiij strongly with the deep, narrow, ahnost " tnnnel-.shaped," 

 anterior-intercondyhir ^jroove in Trachodoii. The shaft of the femur 

 appears to be somewhat twisted, due to the alteration of the aspect 

 of its surfaces, that which at the proximal end is external becoming 

 at the distal end anterior. There is a small roughened area on the 

 extero-posterior angle of the distal portion of the shaft for the 

 attachment of muscles, and just above the beginning of the inter- 

 condylar depression or groove on the anterior surface is a second 

 roughened patch. The outer surface of the outer condyle is decidedly 

 concave, forming a wide, longitudinal depression at the distal end, 

 in which a large tendon must have passed. 



measurements of Specimen, Cat. No. 581S, U.S.N.M. 



mm. 

 Greatest length of right femur 592 



Greatest diameter of proximal end 190 



Greatest diameter of distal end 178 



The flhia. — The tibia in Camptosaiirns 

 is shorter than the femur, in which respect 

 it may be distinguished from Laosaurus, 

 Dryosmirus, and Hypsilophodon fox'ii. It 

 is constricted medially, but greatly ex- 

 panded at either extremity, the longer axes 

 of the expanded ends being at nearly 

 right angles to one another. The proximal 

 end of the tibia shows a division of the 

 articular surface into two condyles, which 

 project posteriorly, separated by an inter- 

 condylar groove, the internal one (<", fig. 

 34) being the heavier. A large enemial 

 crest (&, fig. 34) projects outward from 

 the upper end of the shaft in front of the 

 external condyle. 



The distal end is divided into two mal- 

 leoli, of which the inner is the shorter and 

 heavier, its articular surface looking down- ^ 

 ward and forward, while the external is 

 longer and thinner and looks directly 

 downward. These are separated on the 

 front surface of the bone by a shallow fig. 34.— right tibia and 

 groove. As in Trkeratops, the outer mal- t!nnf.f ''nf "'' J^''™' 



*= ' ' SAUKUS DISPAR M A R S H. 



leolus falls below the superior border of Cat. no. 5818, u.s.n.m. ; 

 the astragulus. Its flattened anterior sur- ^^ astragulus ; h, TNEmAL 

 face was in contact with the distal ex- crest; c, inner condyle. 



, ., c 1 ni 1 rrn • Prom a photograph. 



tremity or the fibula. Ihe posterior sur- 

 face of the distal end of the tibia is angularly convex transversely. 



