1881.] NATURAL SCIENCES OF PHILADELPHIA. 143 



genial, g, and liippocampal, h, are seen on the mesial surface 

 (fig. .3). Let us suppose, now, that that the calloso marginal from 

 the mesial surface and the ascending branch of the supra-sylvian 

 blend with the coronal and that at the same time, while the des- 

 cending branch of the supra-sylvian lengthens, the posterior limit 

 shortens, we shall transform the typical ungulate brain into that 

 of the Pig, Sus scrofa. On the other hand, should the posterior 

 branch of the supra-sylvian lengthen while the descending branch 

 shortens, the result will be the brain of the Cotylophora. The 

 Peccary, Dicotyles, dilfers from the Pig in that the calloso mar- 

 ginal only joins the coronal, and that often at least, the des- 

 cending branch of the supra-sylvian is wanting. In most of the 

 Cervidffi the ascending limit of the supra-s^dvian runs into coronal. 

 From this brief resume it will be seen that fundamentall}^ the 

 brain is constructed on the same pattern in the Pig, Peccary, Sheep, 

 Camel, Giraffe, Deer, etc. 



Let us now try to show that the brain of the Hippopotamus 

 does not essentially differ from the tj^picai ungulate brain to a 

 greater extent than that of the animals just referred to. The 

 most striking feature of the brain of the Hippopotamus, viewed 

 from its upper surface, is the deep fissure, I co (PL XVI), that 

 runs from the posterior to the anterior part of the brain, and 

 rather in an oblique direction, being situated nearer the great 

 longitudinal fissure anteriorly than posteriorly. This fissure 

 serves to divide the upper surface of the hemisphere into two 

 parts, very much as the interparietal fissure does in man ; compared 

 with the type of the ungulate brain, this fissure is evidently due, 

 as suggested by Garrod,^ to the lateral and coronal fissures running 

 into eacli other, wliich I find they almost do in the Camel, Giraffe, 

 Deer and Ox. On the right side of the Hippopotamus' brain 

 examined by me, this fissure runs farther forward than on the 

 left. In the ungulate brain there are usually found between the 

 lateral fissure, that is, the posterior part of the fissure just de- 

 scribed, and the great longitudinal fissure, one or two secondary 

 longitudinal fissures. On the left side of the brain in the Hippo- 

 potamus a secondary longitudinal fissure may be seen, extending 

 forward to about the usual extent, but on the right side this, m I 

 (PL XY I), runs forward anteriorly until it passes between the coro- 

 nal and the great longitudinal fissures. In this respect my specimen 



^ Op. cit., p. 15. 



