614 LAND MAMMALS IN THE WESTERN HEMISPHERE 



As a rule, the teeth of the Santa Cruz armadillos were of 

 the same simple, cylindrical form as in the modern genera and 

 arranged in the same way, but there were some exceptions. 

 In the horned \Peltephilus, the teeth of each jaw were so in- 

 serted as to form a continuous series around the sides and front 

 of the mouth ; and, at first sight, it would seem that this genus 

 differed from all other known edentates in having a full set of 

 incisors, but actually it had but one on each side above and 

 below, as has the modern Dasypus, with the difference that, in 

 the latter, the incisors of the opposite sides are widely sepa- 

 rated and in ^Peltephilus were brought close together. The 

 anterior upper teeth were long and sharp and passed outside 

 of the lower ones, when the jaws were closed, and all the teeth 

 had an external layer of hard and shining dentine, which had 

 almost the appearance of enamel. Another variant in den- 

 tition was ^Proeutatus, which was the largest of Santa Cruz 

 armadillos and larger than any existing forms except Priodontes 

 and Cabassous. It had teeth like those of the huge Pliocene 

 and Pleistocene '\Chlamydotherium, of which it was a probable 

 ancestor; the five posterior ones in each jaw were of trihedral 

 shape, and the two kinds of dentine, of which they were com- 

 posed, were so arranged as to form a rough grinding surface. 

 Probably this animal subsisted largely upon vegetable food ; 

 at all events, the food was of such a nature as to keep the teeth 

 worn down more than in any of the associated genera. A 

 fourth type of dentition was displayed by \Steg other ium (Fig. 

 243, p. 480) ; the teeth were so few and small that they can have 

 had no functional value and were merely minute points almost 

 level with the gums. In all probability, ^Stegotherium was 

 more exclusively insectivorous than the other genera. 



Among the Santa Cruz armadillos may be distinguished 

 four well-marked types of skull. (1) That which agrees closely 

 with the modern form, especially as exemplified by the genus 

 Dasypus. (2) \Proeutatus had a higher and less flattened 

 cranium and a very long, cylindrical muzzle. (3) In the horned 



