EDENTATA OF THE SANTA CRUZ BEDS. 253 



The skulls of Gravigrada, six in number, which Mr. Hatcher collected 

 at Lake Pueyrredon, appear with one exception, to belong to species dif- 

 ferent from those which have been found on or near the Atlantic coast. 

 The specimens, all of which are in a hard concretionary matrix, are not in 

 a very satisfactory state of preservation and have suffered more or less 

 distortion from pressure. No two individuals are alike and, in the 

 absence of much more extensive materials, it is extremely difficult to 

 determine how many species are represented. The exception noted above 

 is a small skull (No. 15,525) which agrees very well with H. gracilidens 

 from the coast region. Of the others, one is a very well marked species 

 and is described below as H. vulpiceps, and the remaining four may be 

 provisionally assigned to one species, H. platycephalus, for, though they 

 are quite dissimilar in size and -appearance, these dissimilarities are evi- 

 dently in part due to differences of age, in part t6 the varying direction 

 and amount of the pressure to which they have been subjected ; the 

 remaining differences should probably be ascribed to the variability which 

 is so striking in the entire group. 



HAPALOPS VULPICEPS sp. nov. 



(Plate XLIV, Figs, i, la, \b.} 



In the proportions of the skull this species differs notably from all 

 other known Santa Cruz Gravigrada, rather resembling, especially in 

 side-view, the skull of a carnivore. Of the dentition, the upper series is 

 represented by -, broken to the level of the jaw, - and - intact and the 

 empty alveoli of ^ and -; all the lower teeth are preserved in a more or 

 less broken condition. 



The upper caniniform (-) is relatively large and, though separated from 

 4 by a considerable diastema, is yet implanted unusually far behind the 

 anterior end of the palate, farther than in any other species of the genus ; 

 in cross section this tooth is a longitudinal, much compressed oval ; - is 

 relatively small and of transversely oval form; - and -, which were 

 evidently much larger than -, were apparently of almost equal size, and 

 - is small and much compressed antero-posteriorly. In the mandible T is 

 small, obscurely trihedral, with two faint vertical grooves, which demar- 

 cate an external pillar; 2 and ^ are quite large 'and transversely rect- 

 angular, while T has the usual subcylindrical shape. 



