40 PATAGONIAN EXPEDITIONS: PALAEONTOLOGY. 



apart. The type and only known specimen, which belongs to the Mu- 

 seum of La Plata, consists of a fragment of the right half of the mandible, 

 including the posterior part of the horizontal and the anterior part of the 

 ascending ramus ; it has two well-marked alveoli and, apparently, the rem- 

 nants of several others that had partly closed after the loss of the teeth. 

 Uncharacteristic as this fragment is, there seems to be sufficient reason for 

 referring it to the present genus ; its specific distinctness is indicated by 

 the greater depth and thickness of the horizontal ramus and by the thicker 

 anterior border of the ascending ramus. 

 Mandible, depth at last tooth, .0086. 



thickness at last tooth, .004. 



DASYPODID&. 



As in the recent fauna, this family was in Santa Cruz times much the 

 most abundant in numbers and varied in genera and species of all the 

 contemporary armadillos. It varies greatly in the size of its members, 

 from the exceedingly small Prozaediuslo the very large and robust species 

 of Proeutatus. 



PROEUTATUS Ameghino. 



(Plates VII-XV.) 



Eutatus Ameghino, non Gervais ; Enumeracion Sistematica, etc., 1887, 



p. 25. 

 Proeiitatus Ameghino ; Revista Argentina de Historia Natural, 1891, p. 



327- 

 Thoracotheriiim Mercerat; Revista del Museo de La Plata ; Tom. II, 1891, 



p. 42. 

 Etitatus, Lydekker, in part; Anales del Museo de La Plata, T. Ill, 1894, 



p. 62. 



This is the most abundant and the most varied of the Santa Cruz arma- 

 dillos and is represented in the collection by several remarkably well pre- 

 served specimens, which permit a very full account of the skeleton to be 

 given, the only parts concerning which information is imperfect being the 

 carapace and the tail. This lack of fairly complete carapaces is especially 

 unfortunate, for most of the species have been established upon the differ- 

 ences in the sculptural pattern of the scutes, and this varies so much in 



