240 PATAGONIAN EXPEDITIONS '. PAL/EONTOLOGY. 



MEASUREMENTS. 



Length of diastema between A and ? . . .014 A , width 0075 



1, length (/'. e., antero-posterior diam- Lower dentition, length 033 



eter) 0055 " " " ^_ 022 5 



" width (/. e., transverse diameter). .. .005 Diastema between T and j, length 0065 



i, length 006 T , length 0045 



" width 0065 " width. 004 



i, length 006 j, length 006 



" width 0075 " width 008 



A length 005 



What little remains of the skull differs hardly at all from that of H. 

 elongatus except in size ; the rostrum is a little shorter and wider and the 

 preorbital fossae rather deeper than in most individuals of the latter, but 

 it is extremely probable that the premaxillae were decidedly shorter. The 

 jugal has the same general shape as in H. elongatus, with the usual broad, 

 descending, suborbital plate ; the posterior process is, however, quite 

 different, being broader and more compressed, much less slender and rod- 

 like; while the notch for the insertion of the zygomatic process of the 

 squamosal is much better defined. The mandible is shorter and wider 

 than in H. elongatus and has quite a different type of predentary beak ; 

 this beak is shorter, broader behind, narrowing forward much more 

 rapidly, and ending in a point instead of a rounded border ; the edentu- 

 lous margins are much more everted or flared and the symphysis is less 

 deeply excavated on the dorsal side. In side-view, the short beak gives 

 to the mandible quite a different appearance. The postero-external open- 

 ing of the dental canal occupies the same relative position as in H. 

 elongatus. 



MEASUREMENTS. 



Zygomatic arch, length 060 Mandible, width of predental beak in 



Skull, width over lachrymals 045 " front of T 021 



Rostrum, width at base 028 " depth of ramus below 3- 022 



" over 1 029 " thickness of ramus below 3-. .013 



Mandible, length of predental beak .. . .0225 



The type of Xyophorus simus is a similar, uncharacteristic fragment of 

 the mandible, which, though considerably larger than that of X. rostratus, 

 may very well belong to an old individual of the same species. 



