SYNOPSIS OF THE VEIiTKUKATE FAUXA OF THE TUEKCO SEKIES. ."Jll 



HEMIGANUS Oope. 

 Amcr. Naturalist, 1882, p. 831 : Tertiary Vertebrata, 1885, PI. XX HI c, figs. 7-13 ; Amer. Naturalist, 1885, p. 4!1l'. 



The claws are large and compressed like those of a prehensile-footed carnivore. 

 The astragalo-tibial articulation is nearl}' flat. The femur is ver}- robust, and has a 

 low third trochanter, as in Bunotheria generally. The vertebr;e of the neck are short 

 and wide. The jaws liave a very lai'ge and wide coronoid process, as in Calamodon, 

 and the horizontal rami are very robust. Only one true molar (the tirst) is preserved, 

 and it has the crown worn. Its outline is subround, with a notch on the internal side. 

 There are probably but two true molars ; they have two roots. There are at least four 

 premolariform teeth, and their crowns are short, obtuse cones, with a low heel-like 

 expansion at the inner side of the posterior base, and have but a single root. They 

 resemble very nearly the teeth of some of the eared seals. There is a robust canine 

 tooth in the upper jaw, which is not separated from the premolars by a diastema. 

 There is at least one superior incisor, but the exact number is unknown. There is a 

 large tooth on each side of the symphysis of the lower jaw, but in the specimens it 

 is not in place. It has enamel on the anterior face only, and its apex is worn ti'ans- 

 versely. The wear descending passes to one side of the middle line. It evidently 

 has a median position, and may be therefore an incisor. Its form reminds one of that 

 of the second inferior incisor of Calamodon, but the enamel-face is much shorter. 



Should the lai'ge inferior teeth be canines, the mandibular dentition will greatly 

 I'csemble that of the seals, as does that of the maxillary bone. The absence of })ost- 

 orbital angles resembles the condition in the Phocidaj. The wide vertical coronoid 

 process and the flat vertical angle are as in Calamodon. The sagittal crest is ele- 

 vated, and the brain-case very small. 



This genus resembles in several respects the Tseniodonta, and confirms the pro- 

 priety of the union of that group with the Creodonta into the ordei' Bunotheria. 



The typical species, H. vuUuosus, was an animal of probably the size of a grizzly 

 bear. A second and considerably smaller species is described below. 



IIemioanus OTAKiiDENS Cope ; Aiiicr. Naturalist, 1885, p. 495. llujus operis, Plates IV and V. 



Only one individual of this species has been found, but it is represented by many 

 parts of the skeleton. It was a plantigrade beast of about the size of a black bear, 

 of robust proportions, and with a wide head with an exceedingly short thick muzzle, 

 armed with some formidable teeth in front. These, with its sharp claws, made it the 

 most formidable animal yet known of the Piierco fauna, excepting its larger and 

 more powerful congener, the H. vultuosus. 



The nares are well roofed by the nasal bones, which border the premaxillarieR 



A. I'. S. — \()L. XV I. 2n. 



