BRAIN OF A FOSSIL UNGULATE, 885 



be a. thick bone, and it is scarcely thinned by the shallow 

 pituitary fossa. 



On the dorsal surface of the skull the frontals form a flat 

 arrowhead-shaped ai'ea between the post-orbital ridges. Laterally 

 they are concave. Below, they unite by suture with the ali- and 

 orbito-sphenoids, and they extend well down on the skull since 

 the palatines cannot be traced below them. Within the skull 

 they form the division between the olfactory and cei-ebral 

 cavities. In front and above they are hollowed out by the 

 frontal air-sinuses. 



The orhitos'phenoid is quite siuall. Its suture with the ali- 

 sphenoid is not plain, but it appears to completely surround the 

 optic foramen. It is indistinguishably fused with the presphenoid, 

 which is a very long and thin bone with a marked median palatal 

 ridge. It is very thick, and its upj)er surface., as seen in section, 

 is shaped like the roof of a house, that is, its surface is very high 

 in its middle length and slopes down both foi- wards and backwards 

 (text-fig. 154, p. 882). The posterior slope shares in the tunnel for 

 the optic nerve, while the anterior one is excavated by a rounded, 

 undercut hollow which gives a firm support to the cribriform 

 plate (cr.p.). This last bone is a solid mass of perfora,ted tissue 

 and presents no special points of interest. 



Comparison of the specimen with the figures given by 

 Cuvier [1] and Blainville [2], as well as with the casts available at 

 the British Museum, leaves little doubt but that the skull has been 

 correctly identified. In Cuvier's figures the general form of the 

 skull with the postorbital constriction, the foi^m of the condyles, 

 the immense paroccipital processes, the peculiar formation of the 

 meatus, the post-glenoid process, its foramen, and a host of other 

 details are identical. Fig. 1, pi. xlvi. of Cuvier's 1822 edition 

 shows the upper surface of the base of the skull of an Anoj^lo- 

 thermm determined from the teeth, and the arrangement of the 

 foramina, of the grooves for the nerves, arid of the transverse 

 sinus agree precisely with this specimen. The agreement with 

 Blainville's figures is no less conclusive, and though the crests on 

 the skull are considerably stronger than those in any specimen 

 figured bv these writers, they are of the same form, and their 

 degree of development can hardly be of greater than specific 

 value when other features agree so markedly. 



Support for the identification also comes from the brain-cast, 

 for it agrees essentially with the natural one figured by Blainville 

 on plate ii., but not with the one given by Cuvier (plate Iv., 

 1822 edit.), which is incorrectly identified as an Anoplothere. 



Bram-cast. 



The narrow, elongate form of the skull is naturally also a 

 feature of the brain. Its total length from the front of the 

 olfactory bulbs to the caudal end of the ceiebellum is a fraction 

 under 10 cms. Of this total, the cerebrum accounts for 5'6 cms., 



