15 



Probably belonging to the same species, and perhaps to the same individual, are the 

 greater part of the frontal and nasal bones, with horns, and the right posterior base of the 

 skull, with part of the zygoma. The first-mentioned fragment shows that the species dif- 

 fers from the Symborodonles trigonoceras and acer, Cope, and the Menodus americanus Leidy, in 

 the absence of angulation above, between the free and other parts of the nasal bones. It 

 also clearly differs from the S. trigonoceras in the semi-erect horns, with little pronounced 

 triangular section. From the S. bucco the lack of expansion of the zygomatic bones dis- 

 tinguishes it. As compared with the S. altirostris, Cope, it has much longer and wider 

 nasal bones, and the horns are more widely separated. The compression makes their 

 apices anteroposterior, while they are transverse in the S. altirostris. 



The ascription of long bones in the collection to this species is more or less uncertain, 

 although a considerable number of pieces which correspond in size with the parts 

 already described probably belong to it. A nearly complete tibia, and the proximal part of 

 a second, may be with great probability assigned here. As already remarked, it differs 

 from those previously described in having the crest divided vertically with a deep grove. 

 The external side is rather the most prominent. A considerable callus occupies the pop- 

 liteal region posterior to the spine and the external cotylus, from the latter of which it is 

 marked off by a groove. The anteroposterior diameter of the external cotylus is greater 

 than the transverse. Below the crest the section of the shaft is triangular, with obtuse 

 angles anterior and exterior. This tibia is much like one which I obtained in Colorado, 

 near to the skulls of several species of Symborodons. A femur which accompanies the 

 Cypress Hill tibia is of smaller size than that described under M. proutii, and is appro- 

 priate to the former. A similar femur accompanies the Colorado tibia. It resembles the 

 one described under the M. proutii in having the great trochanter considerably less pro- 

 minent than the head. 



Measurements of Femur, in Mm. 



Cypress Hills. Colorado. 



Anteroposterior diameter of head x 95 



'' " of great trochanter x SO 



Width of head and great trochanter x 145 



Distance from head to little trochanter, inclusive x 2x5 



Width at condyles , 110 x 



{Anteroposterior. 43 x 



Transverse 65 x 



Measurements of Tibia. 



Total length (with spine) 325 415 



( Anteroposterior (with crest) 125 115 



Proximal diameters < 



(. Transverse, about. .. 115 110 



( Anteroposterior 47 60 



Least diameters of shaftj 



( Transverse 55 55 



C Anteroposterior (at middle) 53 67 



Distal diameters i 



(. Transverse (at middle) 78 SO 



Four astragali and three calcanea are appropriate in size to the M. angustigenis. The 

 former have the ridge dividing the cuboid and navicular facets more prominent than in 

 either of the two large species first described, so that it forms a sharply-angulate pro- 

 tuberance. The cuboid facet forms a wide and less oblique triangle. The navicular facet 



