32 PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 



enclosed by it. The great trochanter is high and thick, rising well above 

 the level of the head, though hardly so large proportionately as in Tatu; 

 the digital fossa, though better defined than in the latter, or in Dasypiis, 

 is extremely small and shallow. The second trochanter is a long, prom- 

 inent, rugose ridge, which is more widely separated from the head and is 

 longer proximo-distally, but much less prominent than in Dasypiis. The 

 third trochanter has about the same relative position as in Tatu, but is 

 not so prominent, nor so much curved forward. The shaft is very broad 

 and much more compressed antero-posteriorly than in either of the last 

 named modern genera; it has a very decided outward curvature, which 

 would be regular, were it not for the second and third trochanters ; aside 

 from the former, the inner border is quite regularly concave, while below 

 the third trochanter on the outer border is a sharp ridge, which ends in 

 the tuberosity. The anterior face of the shaft is much less convex than 

 in Tatu and the posterior face is nearly flat. The rotular groove is broad 

 and shallow, decidedly more so than in Dasyptis or Tatu, being almost 

 plane transversely ; there is no suprapatellar fossa. The condyles, which 

 are widely separated, are small and of unequal size, the internal one con- 

 siderably larger than the external. 



As in the armadillos generally, the tibia and fibula (Plate IV, fig. 6) 

 are coossified at both ends. The tibia is of nearly the same length as the 

 femur exclusive of the great trochanter ; the proximal facets are of nearly 

 equal size, but of different shape ; the external facet is convex and the in- 

 ternal is at a lower level and concave ; there is no tibial spine other than 

 a slight elevation of the mesial border of the inner condyle. The cnemial 

 process is long and prominent and is continued into a ridge which reaches 

 to the distal end, as in Tatu. The shaft is strongly arched toward the 

 inner side and is moderately curved forward ; its external border is a ridge 

 distinct from that which fuses with the fibula. On the postero-internal 

 angle of the distal end is a deep tendinal sulcus between the internal 

 malleolus and the posterior tongue-like process. The astragalar surface 

 is broad, but much compressed antero-posteriorly, and is divided into two 

 facets, of which the external one is deeper and more concave ; the inter- 

 condylar ridge ends posteriorly in a tongue-like process, which is much 

 more prominent than in Tatu. 



The fibula is laterally compressed and plate-like ; the distal end, which 

 forms a heavy external malleolus, bears a small but distinct facet for the 

 calcaneum ; the sulcus for the peroneal tendon is very obscure. 



