y. ' SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 54, NUMBER 7 PeoChiP TON OFA NEW SPECIES. OF HIPPOPOTAMUS WITH FOUR PLATES BY GERRIT S: MILLER, JR. Curator, Division of Mammals, U. S. National Museum (PUBLICATION 1927) CITY OF WASHINGTON PUBLISHED BY THE SMITHSONIAN INSTITUTION March 28, 1910 — ae | et ell CO ee $d TE a eS ek a OS DESCRIPTION OF A NEW SPECIES OF HIPPOPOTAMUS iid By GERRIT S. MILLER, Jr, Curator, Division oF Mammats, U. S. Nationa, Museum (With Four PLatEs) Two skulls of Hippopotamus in the U. S. National Museum, one from the Zambezi River, the other from Angola, differ noticeably from each other in important details of form. Hitherto the exact value of these characters could not be determined, owing to lack of material to illustrate the normal variation in individuals from one locality. The series of eight skulls from British East Africa col- lected by the Smithsonian African Expedition shows conclusively that individual variation in this genus is not unusually great, and that the Zambezian and Angolan specimens must be regarded as representing distinct species. In all essential characters the Zam- bezian skull agrees with those from British East Africa; these are for the present assumed to represent true Hippopotamus ampilubius of the upper Nile.1 The Angolan animal may be known as: HIPPOPOTAMUS CONSTRICTUS, sp. nov. Type—Skull of immature male (m3 not fully in place), number 34747, U.S. National Muséum; collected in Angola, Africa, by H. Chatelain. Diagnosis —Skull in general like that of Hippopotamus amphibius, but rostral constriction deeper, dorsal surface of cranium more flat- tened, difference in level between anterior border of maxillary and of premaxillary more pronounced, and mandibular symphysis much shorter, its median length less than one-third length of mandible; teeth smaller than in Hippopotamus amphibius, the transverse diam- eter of m? scarcely more than one-half that of palate. Skull—rThe skull is throughout less robust than that of Hippo- potamus amphibwus, a peculiarity equally noticeable in dorsal, ven- tral, or lateral aspect; depth at level of anterior border of orbit contained about 4 times in condylobasal length, instead of 3% times, as in H. amphibius; rostral constriction very pronounced, its least *This paper is the seventh dealing with the results of the Smithsonian African Expedition. SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 54, No. 7 2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 4 breadth contained nearly 7 times, instead of about 5 times in con- dylobasal length; anterior portion of rostrum less expanded than in H. amphibius, the ratio of breadth across canines to zygomatic breadth about 77, 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. amp/lubius, 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. amp/lubuus, 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 symphysis to — length of mandible (from articular process to front of alveolus of canine) about 27, instead of about 35. Teeth—tThe 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) ;? zygomatic breadth, 435+ (435); rostral constriction, 110 (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, 44.7x 41.3 (45.5 45.5); second upper — 7 Measurements in parentheses are those of the adult male Zambezian skull (No. 123387). . NO. 7 NEW SPECIES OF HIPPOPOTAMUS—MILLER 3 molar, 53.4 45.4 (51.0 x 50.8) ; first lower molar, 46.2 x 31.0 (51.4 X 33.8) ; second lower molar, 59.0 x 35.4 (57.0 x 38.6); width of palate at anterior lobe of m', 68.2 (76.2). Remarks.—At present there appear to be three well-marked species of Hippopotamus recognizable among the living members of the genus: (a) True Hippopotamus amphibius*® of eastern and north- eastern Africa, (b) H. constrictus of Angola, and (c) H. australis* Duvernoy of the Cape region. The last I have not seen, but, so far as can be judged from the descriptions of Desmoulins and Duver- noy, it is a form in which the flattening of the cranium is carried even further than in H. constrictus, the orifice of the orbit is wider than high, and there are certain important peculiarities in the inter- relations of the upper and lower canines, and in the form of the anterior cheek-teeth. ° Synonymy : 1758. Hippopotamus amphibius Linnaeus, Syst. Nat., I, roth ed., p. 74 . (Nile). 1846. Hippopotamus typus Duvernoy, l'Institut, XIV, p. 333. October 7, 1846 (“Senegal or Abyssinia”). * Synonymy : 1846. Hippopotamus australis Duvernoy, l'Institut, XIV, p. 333. Octo- ber 7, 1846. (Previously described but not named by Desmou- lins, Journ. Physiol. Exp. et Path., V, p. 354, October, 1825.) SMITHSONIAN MISCELLANEOUS COLLECTIONS HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER HIPPOPOTAMUS CONSTRICTUS. TYPE SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54, NO. 7, PL. 2 HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER HIPPOPOTAMUS CONSTRICTUS. TYPE SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54, NO. 7, PL. 3 HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER HIPPOPOTAMUS CONSTRICTUS. TYPE SMITHSONIAN MISCELLANEOUS COLLECTIONS HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER HIPPOPOTAMUS CONSTRICTUS. TYPE oe LE D 10 ro, eae ; SMITHSONIAN MISCELLANEOUS COLLECTIONS VOLUME 54, NUMBER 7 } || DESCRIPTION OF A NEW SPECIES OF al HIPPOPOTAMUS WITH FOUR PLATES GERRIT S. MILLER, Jr. Curator, Division of Mammals, U. S. 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