EDENTATA OF THE SANTA CRUZ BEDS. 251 



MEASUREMENTS. 



No. 15,525 No. 15,529 



Skull, width at postorbital constriction 026 .029 



" " over lachrymals .041 



Zygomatic arch, length 055 .054 



Palate, width at -1 .012 



" " " preorbital fossae .018 



" " "2 on .012 



" " "..._. on .on 



HAPALOPS FORTICULUS Ameghino. 



Psetidhapalops forticulus Amegh. ; Rev. Argent, de Hist. Nat., T. I, 



1891, p. 319. 



Pseudhapahps altiramis Amegh. ; 6num. Synopt. des Mamm. Foss. de 

 Patagonie, 1894, p. 150. 



The most characteristic feature of this species is to be found in the 

 shape of the lower caniniform tooth (-) which is large and laterally com- 

 pressed and projects from the side of the jaw almost as much as in some 

 of the species of Eucholaops. The mandible has an extremely short pre- 

 dental beak and the profile of the chin curves uninterruptedly into the 

 ventral border of the horizontal ramus, the two together describing a con- 

 siderable segment of a circle. The postero-external dental foramen is 

 large and opens laterally, not anteriorly, and is placed in an unusually 

 inferior position, upon the side of the horizontal ramus below the base of 

 the coronoid. 



In the collection of the La Plata Museum is a portion of the lower jaw 

 which agrees quite exactly \vith the type of the present species. 



The specimen to which Ameghino has given the name Pseudhapahps 

 altiramis (loc. cit., p. 150) appears to be merely a more robust and older 

 individual of the present species, with lower caniniform of more triangular 

 and less laterally compressed shape. 



MEASUREMENTS. 



Type. P. altiramis. 



Lower dentition, length 039 .037 



" " " j_j 022 .023 



T , length (i. e., antero-posterior diameter) 007 .007 



" width (i. e., transverse diameter) .005 



j, length 0065 .006 



7 , length 006 .006 



" width 009 



