1895.] ^OL [Cope. 



Hypopnous squaliceps, sp. nov., PI. viii, Figs. 3-5. 



Based on a skull, which is somewhat crushed by pressure. The bony 

 roof of the anterior part of the muzzle has been lost. The suspicion that 

 physical causes could have produced the extraordinary form of the 

 muzzle is dispelled by the symmetry of all the parts, and the preservation 

 of the much abbreviated right mandibular ramus, which is perfect except 

 the angle, with its teeth. 



The cranium is moderately elongate, is truncate posteriorly, and has a 

 rather broadly rounded muzzle. The orbits are posterior to the middle 

 transverse line of the skull, and have the axis directed at an angle of 45° 

 to the horizontal plane of the skull. The anterior border of the mouth is 

 below the anterior border of the orbit. The nares are large ; their ante- 

 rior border coincides with the border of the muzzle, and they are about 

 as wide as long, the width equaling that of the premaxillary space 

 between them. The mouth border is 1.33 times their long diameter pos- 

 terior to them. The diameter of the orbit is one half the long diameter 

 of the muzzle, and enters its width one and one-half times ; it equals the 

 length of the cranium posterior to it, and is twice the interorbital width. 

 Both ossa quadrata are preserved j they are directed outwards at an angle 

 of about 45°. Their articular surfaces are concave transversely and 

 plane anteroposteriorly ; the anterior border is concave, the posterior 

 convex. 



At the anterior extremity of the mandible there is a series of three 

 teeth, which are relatively large, since their length exceeds the depth of 

 the ramus. Their shanks are cylindric, and the apices conic. The last 

 two are opposed by two teeth of the upper jaw, and behind these is a 

 third. These are well under the border of the skull, and it is likely that 

 they belong to the palatine bone, although this is not demonstrable. 

 Posterior to the three mandibular teeth are two others, but it is uncertain 

 whether they are mandibular or palatine teeth. The crowns of the latt 

 two anterior palatine teeth are compressed, as in the species of Pario- 

 tichus. 



The surface of the cranial bones is sculptured in a shallow honeycomb 

 pattern, the longitudinal ridges predominating on the median regions pos- 

 teriorly. These bones with those of the mandible are rather abundantly 

 marked with deeply impressed puncta, which may be in some instances 

 pores. These are larger and more numerous on the malar bone, where the 

 sculpture is wanting. They are more sparse on the mandible, and become 

 larger anteriorly. Tiie surface of the ramus is marked also with shallow, 

 generally longitudinal grooves, which sometimes inosculate, and some- 

 times terminate in the punctiform pits. The inferior bones of the muzzle 

 are sculptured like those of the interorbital region. 



A series of five crushed vertebrre lie along the inner side the left man- 

 dibular ramus, displaying only their neural arches. They are about as 

 wide as long, excepting the anterior one, which is longer. The zyga- 

 pophyses are well developed, and there extends from about the middle of 



