EDENTATA OF THE SANTA CRUZ BEDS. 245 



Laterally, the occipital crest is quite prominent, but it dies away dor- 

 sally ; the supraoccipital is reflected far over upon the dorsal side of the 

 cranium, especially in one of the specimens (No. 9,293) in which this 

 reflection is carried to an unusual extent; the condyles are small and 

 nearly sessile and the paroccipital processes are obsolete. The squa- 

 mosals and frontals do not differ in any important manner from those of 

 H. elongatus, while the lachrymals are rather smaller and less prominent. 

 The nasals are broad posteriorly, where their sutures with the frontals 

 form two straight lines meeting at a very open angle; anteriorly they 

 have blunt median points and deep lateral notches, making very long 

 lateral processes, which project beyond the edge of the anterior nares. 

 The premaxillaries are of the type usual in this genus, but with certain 

 characteristic features ; they are distinctly shorter and heavier than those 

 of H. elongatus, the postero-external branch is heavier, the spine is more 

 slender and the anterior branch is shorter. The maxillaries differ little 

 from the other small species of the genus, except that they have a shorter 

 facial portion than in H. elongatus and that, usually, the preorbital fossae 

 are narrow and shallow. The palatines are very thick and a peculiar, 

 smooth surface slopes upward and backward from the level of the palate 

 to the margin of the posterior nares ; this surface is variable in extent and 

 is much more distinctly shown in some individuals than in others. The 

 hard palate is of nearly uniform width between the molariform teeth, the 

 two series of which are almost parallel ; the degree of roughness and con- 

 vexity of this region varies much, perhaps according to the age of the 

 individual. The front margin of the posterior nares is placed somewhat 

 farther back than in most of the species. 



The mandible is still incompletely known ; its most characteristic 

 feature is the position of the postero-external opening of the dental canal, 

 which presents laterally and is placed at the base of the ascending ramus. 

 From the length of the premaxillaries it may be inferred that the predental 



beak was short. 



MEASUREMENTS. 



Type. No. 9,293. No. 9,250. 



Skull, length in median line, including premaxillae .126 



" excluding " 105 .108 .105 



" occipital condyle to anterior nares 124 .128 .124 



to end of premaxillae . 1 36 



Cranium, length occipital condyle to edge of orbit 094 .099 .094 



Face, length orbit to anterior nares 034 .03 1 .034 



