EDENTATA OF THE SANTA CRUZ BEDS. 243 



accidental association and is referable to some much smaller species, per- 

 haps of a different genus. 



HAPALOPS RUETIMEYERI Ameghino. 



(Plates XXXVII, Figs. 4, 6 ; XXXVIII, Figs. 4, 6 ; XXXIX, Figs. 4, 4, 6, 6" ; 



XLII, Figs. 4-8.) 



Hapalops ruthmeyeri [sic] Amegh.; Rev. Argent, de Hist. Nat., T. I, 



1891, p. 153. 

 Pseudhapalops rtdimeyeri Amegh.; fenum. Synopt. d. Mamm. Foss. de 



Patagonie, 1894, p. 151. 

 Pseiidhapalops ruetimeyeri Lydekker ; Anales del Museo de La Plata, T. 



Ill, 1894, p. 101. 

 Pseudhapalops observations Amegh.; Rev. Argent, de Hist. Nat., T. I, 



1891, p. 319, 



Geronops circularis Amegh.; Ibid., p. 320. 

 Eugeronops circularis Amegh.; Ibid., p. 397. 

 Pseudhapalops circularis Amegh., Sec. Censo de la Repub. Argent., T. 



I, 1898, p. 199. 



This is a small species, considerably smaller than H. elongatus and dif- 

 fering from the latter not only in the position of the external dental fora- 

 men of the mandible, but also in several details of structure of the skull 

 and skeleton. A finely preserved specimen, collected by Mr. Brown for 

 the American Museum of Natural History (No. 9,250), consisting of the 

 greater part of a skeleton, agrees so well with the type, that it may be re- 

 ferred to the same species, though the unfortunate absence of the man- 

 dible prevents the reference from being quite certain. As is almost in- 

 variably the case among the Santa Cruz Gravigrada, there are many 

 individual differences between the two specimens, increased, no doubt, by 

 their difference in age ; in spite of its slightly larger size, the type is 

 a very young animal, with widely open palatal suture, while the New 

 York specimen is thoroughly adult. A third skull, likewise in the collec- 

 tion of the American Museum (No. 9,293) may be provisionally referred 

 to the same species, though it differs in some significant respects from both 

 of the others, and in this case also the absence of the mandible makes the 

 reference uncertain. 



The first upper tooth (-) is quite small and is placed a little farther 

 behind the anterior edge of the palate than in H. elongatus. In two of 



