EDENTATA OF THE SANTA CRUZ BEDS. 95 



and much more prominent on the internal side than in Proeutatus ; on the 

 other hand, the shaft is somewhat more slender and the distal end less 

 thickened than in the latter. 



The radius (Plate XVI, fig. 10) is characteristic; the head is trans- 

 versely oval, but narrower and less produced externally than in Proeutatus, 

 and bears a simple, shallow concavity for the humerus ; for the proximal 

 half of its length, the shaft is slender and subcylindrical, but expands gradu- 

 ally to the distal end, where it forms a broad plate, thus having quite a 

 different appearance from the radius of any other Santa Cruz armadillo ; 

 the styloid process is very short. 



The carpus (Plate XVI, fig. 1 1) is almost identical with that of Proeu- 

 tatus and Dasypus. The scaphoid is very short and broad, extending 

 obliquely beneath the lunar to a contact with the magnum. The lunar, 

 which is also broad and very short, rests principally upon the scaphoid, 

 but articulates also with the magnum and unciform. As usual, the pyram- 

 idal extends beyond the unciform to articulate with metacarpal V. The 

 trapezium is narrow but elongate and has an extensive connection with 

 metacarpal II. The trapezoid is connected with metacarpal III, shutting 

 off metacarpal II from articulation with the magnum, as in Proeutattis and 

 Dasypus. The magnum is shorter and broader than in the former and 

 the unciform is of the usual pyramidal shape, thinning to an edge on the 

 ulnar side. 



The metacarpals are five in number and are somewhat more peculiar 

 than the carpals. The pollex is more reduced than in any other contem- 

 porary member of the order and its metacarpal is short, slender and sub- 

 cylindrical. 



Metacarpal II is heavy and has a more expanded head than in Proeu- 

 tatus, with a large facet on the radial side for the trapezium ; it is of 

 nearly uniform width throughout, but diminishes in thickness distally, 

 where the trochlea is deeply grooved in the median line and has no trace 

 of a carina, but with a deep pit above it on the dorsal side of the shaft. 



Metacarpal III is slightly longer and stouter than metacarpal II, but 

 very like it in form ; the distal trochlea has a faintly indicated carina and 

 a larger dorsal fossa. 



Metacarpal IV is far shorter than in Proeutatus, being less than one half 

 as long as metacarpal III, and also very stout ; its trochlea is as in the last 

 named genus and altogether different from that of metacarpals II and III. 



