14 PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



nearly three times as long as they are wide,- and each scute is clearly 

 demarcated into covered and exposed portions. The anterior, covered 

 portion occupies somewhat less than one half of the length of the plate ; 

 it is considerably thicker than the exposed portion and, on the dorsal side, 

 the line of junction between the two is marked by the abrupt, step-like 

 descent which is usual in the armadillos. Though the small, square plates 

 of the anterior region of the carapace are thus markedly different from the 

 narrow, elongate plates of the middle region, there is no abrupt change, 

 such as occurs in the genera having a definite scapular buckler, but a 

 gradual transition from one to the other. 



The sculpture of the exposed portion of the scutes is very characteristic ; 

 the pattern consists of a very low and narrow, but quite sharp, median, 

 longitudinal ridge, which usually pursues an oblique course, and of raised 

 lateral borders, while the whole exposed surface is finely pitted, or granu- 

 lar. Near the line of junction between the exposed and the covered part 

 of the scute is a transverse row of large and conspicuous piliferous pits, 

 which are of somewhat irregular size and shape, the median one usually 

 being larger than the others. The lateral and posterior borders of the 

 plate are also pitted in an almost continuous line, though these pits are 

 much smaller than those of the anterior transverse row. The appearance 

 of the plates seems to indicate that the animal was in life quite thickly 

 clothed with hair. 



Dentition.- -The teeth, which are of minute size, are of somewhat vari- 

 able number, even on the two sides of the same skull, and combining the 

 two specimens, we get the formula |=|. These teeth are of cylindrical 

 shape and together occupy but a short space in the hinder portion of the 

 jaws, leaving much the greater portion of the latter entirely edentulous. 

 They are not, as in most armadillos, so bevelled by wear as to have a 

 transverse, median ridge, but are worn obliquely from within outward. 

 So extreme is the reduction of the teeth that they can hardly have had 

 any functional importance. 



Skull (Plate II.) On the whole, the skull has more resemblance to 

 that of Tatu than to that of any other existing armadillo, though the elonga- 

 tion of the rostrum and the great attenuation of the jaws produce a certain 

 likeness to Priodontes. The cranium is short, broad and high, the face 

 long, slender and tapering, the extremely slender mandible adding but 

 little to the vertical diameter of the face. When viewed from the side, the 



