2 SMITHSONIAN MISCEIJ.ANEOUS COLLECTIONS VOL. 54 



breadth contained nearly 7 times, instead of about 5 times in con- 

 (lylobasal length ; anterior portion of rostrum less expanded than 

 in H. amphibius, the ratio of breadth across canines to zygomatic 

 breadth about yy, instead of about 88 ; form of rostral expansion 

 differing from that of the related species in the less forward exten- 

 sion of maxillaries, so that level of canines is noticeably further 

 behind that of anterior incisors, and the bases of the three teeth of 

 each side lie nearly in a straight oblique line ; occipital region and 

 dorsal surface of orbits much less elevated above level of median 

 portion of frontals than in H. aiiipliibins, the vertical diameter of 

 orbit not conspicuously greater than transverse diameter ; mandible 

 with posterior portion less developed, both longitudinally and ver- 

 tically, than in the related species, the ratio of height through coro- 

 noid process to length (from articular process to front of alvedus 

 of canine) about 60, instead of about 65 ; posterior border somewhat 

 flattened immediately below articular process, the region of its 

 greatest convexity at level of middle of ramus, rather than above 

 middle ; symphysis both shorter and narrower than in H. amphibius, 

 the longitudinal trough on its upper surface less well defined, the 

 hinder border opposite front of middle premolar instead of front, 

 of posterior premolar, the ratio of median length of sym])hysis to 

 length of mandible (from articular process to front of alveolus of 

 canine) about 27, instead of about 35. 



Teeth. — The teeth are essentially similar to those of Hippopota- 

 mus amphibius, except that they are relatively smaller (transverse 

 diameter of m' scarcely more than one-half that of palate) ; the 

 crowns of the molars are narrower, and the outward curve of max- 

 illary series behind premolars is more pronounced. 



Measurements. — Cranial measurements of type (millimeters) : 

 Condylobasal length, 690 (730) f zygomatic breadth, 435 ± (435) ; 

 rostral constriction, no (144) ; rostral expansion, 332 (370) ; occip- 

 ital breadth, 278 (332) ; occipital depth (to basion), 196 (214) ; 

 median depth between orbits, 181 (208) ; nasal, 390 (400) ; height 

 of orbit, 75 (90) ; width of orbit, 70 (65) ; elevation of orbit above 

 level of forehead, 24 (40) ; mandible (condyle to front of alveolus 

 of canine), 587 (620) ; coronoid height, 355 (410) ; canine width 

 385 (403) ; length of symphysis (without median spine), 168 (224) ; 

 maxillary toothrow (alveoli), 265 (258) ; mandibular toothrow, 293 

 (286); first upper molar, 44.7x41.3 (45.5x45.5); second upper 



^Measurements in parentheses are those of the adult male Zambezian skull 

 (No. 123387). 



