232 PATAGONIAN EXPEDITIONS! PALEONTOLOGY. 



HAPALOPS ANGUSTIPALATUS Ameghino. 



(Plate XLIII, Figs. 2-5.) 



Hapalops angustipalatus Amegh. ; Rev. Argent. Hist. Nat, Vol. I, 1891, 

 p. 316. 



This is another species of doubtful validity, for it may very well prove 

 to be identical with some of the species which have been established upon 

 the mandible alone. The type specimen is the facial portion of a skull, 

 with all of the teeth, except -, in position. In the Princeton collection 

 the species appears to be represented by a specimen (No. 15,562), com- 

 prising a considerable part of the skeleton, which was collected by Mr. 

 Hatcher at Corriken Aike. This individual consists of the skull, of which 

 only the base is preserved, without mandible, seven thoracic and four 

 lumbar vertebrae, parts of the scapula and humerus, the radius, ulna, meta- 

 carpals II and III, femur, patella, tibia and part of the pes. 



H. angustipalatus is distinctly larger than H. elongatus; individuals of 

 the latter yield measurements which form a series of gradations from the 

 smaller to the larger specimens, while the dimensions of H. angustipalatus 

 are separated by a wide gap from those of the largest representatives of 

 H. elongatus. Another difference from the latter is in the relative size 

 and proportions of the skull, which is considerably smaller in comparison 

 with the vertebrae and limb-bones, and broader in proportion to its length 

 than in the last named species. 



The teeth are not especially characteristic; the caniniforms ( A ) are 

 relatively large, sharply pointed by abrasion and are placed somewhat 

 more externally to the line of the other teeth than is usual in this genus. 

 The molariform teeth are large and of more or less distinctly rectangular 

 outline, except & , which is very small and transversely oval. 



The skull is relatively broader than in most examples of H. elongatus 

 and the occipital condyles and foramen magnum are larger, while the 

 basioccipital and basisphenoid are broad and quite flat transversely. The 

 descending processes of the alisphenoids and the pterygoids, which form 

 the side-walls of the posterior nares, are less produced downward than in 

 H. elongatus. The hard palate is more decidedly convex between the 

 molariform teeth than in the latter species and wider between the canini- 

 forms, while the anterior median notch for the premaxillary spines is 

 distinctly smaller. On the other hand, the preorbital fossae of the maxil- 



