BATHMODON. 551 



There is no important difference between the femur and that described 



vinder C. anax, excepting the superior size. The little trochanter is not 



quite so prominent in the larger bone. 



Measurements of femur. 



Length 500 



Width proximally with great trochanter 165 



Transverse diameter of head 085 



Width at third trochanter 105 



Width of shaft below third trochanter 077 



Width at epicondyles 138 



Anteroposterior diameter inner condyle 092 



Anteroposterior diameter outer condyle 074 



The astragalus has the characters of that of B. radians, with an ap- 

 proach to some of those of CorypJiodontes. The internal hook is well devel- 

 oped, and is recurved so that its posteriorly-directed apex is separated by a 

 deep notch from the posterior median tuberosity. In C. latipes and other 

 species the apex is directed inwards and not backwards. This is a well- 

 marked character, and one in which it resembles the Bathmodon radians; 

 but in that species the internal hook is still shorter, though its tibial face is 

 not carried so far posteriorly. The apical facet, mentioned as character- 

 istic of the genus Bathmodon has the same relative size and proportion as in 

 B. radians, but its suiiace is not cut off from the anterior part of the apex 

 by a deep groove, as in that species. A comparison of the inferior side 

 with that of the astragalus of B. radians, displays the following differences : 

 The external facet in the latter is cut off from the posterior tuberosity by a 

 deep groove, which is continued from a deep notch in the posterior border 

 of the bone. In B. pachypus the notch is very shallow, and the groove is 

 not connected with it, the external facet being continuous with that on the 

 inferior side of the posterior tuberosity. The notch is more apparent on the 

 superior than on the inferior side of the astragalus in the B. pachypus. In 

 the latter, the anterior inferior facet is separated by a wide space from the 

 supernumerary internal facet; in B. radians they are almost in contact. The 

 anterior facet is absolutely smaller in the B. pachypus, and is more largely 

 extended on the posterior tuberosity than in B. radians. Both the navicu- 

 lar and cuboid facets have greater transverse extent in the B. pachypus, and 

 the latter extends to behind the middle of the former, which it scarcel}^ does 

 in B. radians. 



