wanting. The probability of the truth ol this determination is increased 

 by the presence of a small interval between them, and by the fact that 

 they oppose the canines of the upper jaw. 



LOXOLOPHODON. Cope. 



Proceedings American Philosophical Society, 1872, p. 580, extra copies 



published August 19th ; and p. 488 (Aug. 22d). 



The cranium in this genus is very elongate and compressed. The 

 muzzle is posteriorly roof-shaped, but is anteriorly concave and flattened 

 out into a bi-lobed shovel which rises above the extremity of the bone. 

 This extremity is subconic, and short and decurved. A second pair of 

 horn-cores stands above the orbits ; each one composed externally of the 

 maxillary bone, and internally of an upward extension of the posterior 

 part of the nasal. Behind this horn the superior margin of the temporal 

 fossa sinks, but rises again at its posterior portion, probably above the 

 level of the middle of the parietal bones. This portion of the skull is 

 injured in my only specimen. The occipital rises in a wall upwards from 

 the foramen magnum, and supports, probably a little in front of the junc- 

 tion with the superior and inferior ridges bounding the temporal fossa, a 

 third horn core on each side. The base of this core is as stout as that 

 above the orbit, and sub-cylindric in section. The temporal fossa has its 

 principal extent posterior to the zygomatic arch, and is in form like a 

 trough, the inferior edge being recurved from the squamosal process to 

 the summit of the occipital crest. It is narrow within the zygomatic 

 arch, which is short, enclosing a space whose length is less than one- 

 fourth that of the cranium. 



The occipital bone extends but a short distance on each side of the 

 condyles, and is separated from the mastoid by an irregular suture, 

 which is pierced by a large mastoid foramen. On the inferior face near 

 to each condyle and one-third the distance from its inner extremity, is a 

 posterior condyloid foramen, isolated by a narrow bar from the extremity 

 of the foramen lacerum posterius. The paramastoid process is repre- 

 sented by a small tuberosity, and the mastoid by a rather larger one, 

 some distance anterior to it. 



The meatus auditorius opens upwards just below the external ridge of 

 the temporal fossa and at a little distance behind the post-glenoid pro- 

 cess. Its canal contracts rapidly, and extends upwards and backwards 

 towards the labyrinth. It is separated from the foramen lacerum by but 

 a thin wall, and if there was an expansion of the cavum tympam, it must 

 have been exceedingly small, owing to the close approximation of the 

 mastoid to ttie basi-occipital and sphenoid at this point. The labyrinth 

 is lodged in a petrous mass opposite the occipito-mastoid suture, and the 

 canals are small. 



The basi-occipital contracts anteriorly, and with the sphenoid forms an 

 uninterrupted boundary of the foramen lacerum. This terminates oppo- 

 site to the posterior boundary of the external meatus. and gives rise to a 



