116 



BULLETIN 89, UNITED STATES NATIONAL MUSEUM. 



From these two parts of opposite humeri it is estimated the total length of 

 the humerus in this individual would be about 385 mm. The greatest transverse 

 measurement of the distal end is 165 mm. 



In the considerable expansion of the ends and the contraction at the center 

 the humerus in Hoplitosaurus resembles those of Polacanthus and Acantlwpholis. 



Femur. — The right femur is almost perfectly preserved, lacking only a portion 

 of the fourth trochanter. It was found in the matrix of the lower side of the block 

 containing the dermal ossifications shown in plate 27. Although only little more 

 than one-half the length of the shortest Stegosaurus femur in the National 

 Museum collections, the proportions of these bones are remarkably similar. The 



Fig. 69.— Right femur or Hoplitosaurus marshi (Lucas). Type. Cat. no. 4752, U.S.N.M. j nat. size. (1) Front 

 view. (2) Back view. (3) External view, a, Lesser trochanter; 6, greater trochanter; h, head; i.e., internal 

 condyle; o. c, outer condyle; I, fourth trochanter. 



articular parts of the proximal and distal ends are in general aspect typically 

 Stegosaurian. The head is not as distinctly separated from the rest of the proxi- 

 mal end as in Polacanthus, but resembles more nearly the conditions found in 

 Stegosaurus; the rugose proximal surface continues uninterruptedly over the 

 entire proximal end to the external border. The lesser trochanter (a, fig. 69) is 

 relatively more strongly developed in Hoplitosaurus than in Stegosaurus. It is 

 characterized by its compression in the direction of the bone; it is roughened exter- 

 nally and divided by a narrow fissure from the neck of the femur. The flattened 

 nature of this trochanter and its external position, on the proximo-anterior face, 

 would at once serve to distinguish it from other femora pertaining to the armored 

 dinosauria. 



