ON THE BONES OF TUE HIPPOPOTAMUS. 377 



2nd. By the projection of the orbital vaults, in two ways, namely 

 above the right line (c, ib.^ so as to make the eyes very much raised, 

 and below the middle line, so as to cause the axes of the orbits to form 

 a sort of cross with it. 



3rd. By the shape of the snout, at first almost cylindrical, (c c, 

 plate 31, figs. 2 and 3), and then suddenly enlarging into four thick 

 turgid excrescences,^ one on each side, to contain the sockets of the 

 incisores (a, ib.) and one more external for that of tlie canine {b, ib.) ; an 

 oblique and deep farrow, (c?), separates these turgid excrescences, and 

 contains the suture, distinguishing the incisor from the maxillary bone. 

 The root of the snout (//, plate 31, fig. 2,) is flattened and 

 widened, to cover the anterior part of the orbits. This widening is 

 fanned by the lachrymal bone, and the base of the jugal. The 

 lachrj'mal bone (jnni, ib.) is rather singular: on the cheek it forms 

 an oblique little tongue, enlarging towards the base; its narrow part 

 bounds the edge of the orbit, where it has a slope, forming in tlie 

 . interior of this cavity another little tongue, which is continued by 

 passing over the posterior aperture of the sub-orbital canal, and ter- 

 minates there by a swoln sinus with delicate partitions ; nevertheless, 

 the lachrymal duct is very deeply hollowed in the bottom of the orbit. 



The temporal fossae are so deep that the skull is moreover some- 

 what less in size than the middle portions of the snout. (See e e, pLite S 1 , 

 figs.2and3). Tliey leave between them a crest in a right line, and the 

 frontal angle (x, fig. 2), which separates them in front, is very obtuse. 

 The frontal is concave between the two orbits. 



The bone of the cheek advances very much upon the face, lower 

 still than the lachrymal, with the side of which it articulates, and forms 

 a pointed apophysis (c?, fig. 2.), which rises behind the orbit, and 

 almost terminates its circle. However, there is a small interval be- 

 tween the summit of the apophysis and the edge of the arch of the 

 eyebrow of the frontal. It is well known that the quadrum^anes, rumi- 

 nants, and the solipedes, are the only animals which have this interval 

 filled by the bone. 



The frontal, after having formed the arch of the eyebrow, continues 

 to form a crest, which proceeds obliquely towards the back, distin- 

 guishing by its projection the temporal fossa from the orbit. This crest 

 is continued on the parietal and sphenoid bone's. The sutures of the 

 frontals and of the parietals form a cross in young subjects. 



The upper occipital advances, in an obtuse angle, between the parie- 

 tals.' There is no interparietal. 



The parietal does not become united to the sphenoid at the bottom, 

 of the temporal fossa, but at an interval of some millimetres. 



The palatine bone re-ascends into the orbit, and there advances in 

 front as far as the lachrymal, by a little tongue. The posterior sphenoid 

 there rises almost as high, and the anterior there' occupies a place 

 above. They are both partly concealed by the descending crest, which 

 continues on the parietal and on the temporal in the temple, that which 

 the fronta.1 had begun on the orbit. 



The zygomatic arch is straight, as well in the longitudinal sense 

 (d e, plate 31, fig. 1), as in its horizontal plane, (f g, ib. figs. 2 and 3); 



