6 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



to Mr. Oldfield Thomas, of the British Museum, for free access to the 

 collections under his charge, and for much valuable assistance. 



Subclass EDENTATA. 



Order DASYPODA. 



Of the Edentates, so numerously represented in tropical America, only 

 the Armadillos reach Patagonia, and of these only a single species is repre- 

 sented in the collections made by the Princeton University Expeditions ; 

 and this finds its southern limit of distribution at the Rio Santa Cruz. A 

 second species of Armadillo, Tatu hybriciiis {Dasypus hybridus Desm.),is 

 recorded from northern Patagonia, and is said to extend as far south as to 

 the Rio Negro, which region, however, is outside of the geographic limits 

 assigned to the present report. 



Not only are the Sloths (Bradypodidae) and the Anteaters (Myrmecopha- 

 gidae) absent from the existing fauna of Patagonia, but, according to Pro- 

 fessor Scott, no trace of them has yet been found in the Santa Cruz beds, 

 in which Armadillos are represented in such great abundance and diver- 

 sity. This seems to show, as stated by Scott, that the true Sloths and 

 Anteaters " must have originated in some other part of the South American 

 Continent and were prevented by climatic or other barriers from extend- 

 ing their range into Patagonia."^ 



The majority of the Armadillos of the Santa Cruz beds "belong to 

 extinct lines," which for the most part "are not known to pass beyond 

 the limits of the Santa Cruz formation." To quote from Professor Scott 

 (/. c, p. 8) in respect to the relationship of the extinct to the modern 

 forms, he says : 



"Attention has already been called to the difference between the Santa 

 Cruz and the recent Armadillos, a diff"erence which can be made clear in 

 a few words. No probable forerunner of Dasypus, Pyiodontes, Tolypejttes, 

 Chlamydophorus, or Tatu, has been found in these beds, though some 

 one of the species of Prozaedius was almost certainly an ancestor of the 

 recent Zaedyus, and it is possible, though far from certain, that some 

 species of Stenotatus stood in the same relation to the modern Cabassous. 

 In view of the stage of differentiation attained by the Santa Cruz Arma- 



' Reports Princeton University Exped. Patagonia, Vol. V, Part I, 1903, p. 4. 



