longation of the muzzle. In front of the zygomatic arches, the form is 

 compressed and roof-like above. Above the tusks the nasals expand, and 

 are produced to a great distance, terminating in osseous prominences. 

 The premaxillaries are also much produced ; their anterior part is slender 

 and toothless, and does not extend so far as the nasals. 



The orbit is not enclosed behind, and has no marked superciliary or 

 other margin. Above it, on each side, a horn-coYe is given off, the pair 

 diverging from approximated bases. Occiput vertical. 



The affinities of this genus are not close to any known, excepting Bath- 

 modon. This has the six premaxillaries of usual proportions, at least 

 three true molars, and the posterior premolars with three crescents. The 

 general relationships are proboscidian, and associated in some measure 

 with Synoplotlierium, AucMppodus and Pseudotomus. 



Besides the L. semicinctus, Cope, originally described, the l-esearches 

 under Prof. Hayden's Geological Survey, have determined the existence 

 of two or three other species of much lai'ger size. 



LOXOLOPHODON CORNUTUS. Cope. 



Eobasileus comutus. Cope. 



Established on portions of several skeletons, including one with femur, 

 pelvis, scapula, vertebrae and cranium. The latter measures about thirty- 

 four inches in length. The horn-cores are very stout and sub-triangular 

 in section at base and with a rudimental knob on the inner side ; height 

 seven inches about. A massive protuberance of a recurved lobate 

 outline rises on the anterior margins of the nasal bones on each 

 side. They meet, leaving an emargination in front, giving the nasal 

 bones a bi-lobed outline. The iliac bones are very wide, the expanse of 

 both together being fifty-four inches . The centrum of a sacral vertebra 

 is four inches in diameter. 



LOXOLOPHODON PURCATUS. Cope. 



This species is indicated by portions of the nasal bones. These have 

 differed in form materially from those of the L. comutus. The convex 

 protuberances seen in L. comutus were here represented by processes of 

 singular form. They were compressed, narrowed at the base, and 

 expanded distally into a flat spatulate body. The whole process measures 

 seven to eight inches in length, and three and a-half in width distally. 



The animal could not have been materially smaller than the L. comutus. 



LOXOLOPHODON PRESSICORNIS. Cope. 



Established on numerous remains, including horn-cores of species simi- 

 lar in size to the last. Its marked peculiarity, as first noticed, consists 

 in the compression of the horn-cores throughout the proximal half of 

 their length, with-.their more acuminate form, than in L. comutus. They 

 measure also about seven inches in length. 



The affinities of these remarkable animals will be shortly discussed. 



They were the gigantic mammals of our Eocene period, representing 

 the Elephants and Mastodons of the Miocene, which they equalled in 

 size. Aug. 22, 1872. 



