AND OTHER PARTS OF HIPPOPOTAMUS. 15 



front to back, not far from the middle line, which it more nearly approaches anteriorly 

 than posteriorly. This continuous fissure must be compound, and made up of the 

 coronal (co) in front, blended with the lateralis (I) behind, between which latter and 

 the splenialis (sp) a secondary longitudinal fissure develops in the usual manner. 

 Though, as far as I am aware, there is no other Ungulate animal with the two above- 

 named fissures actually joined, they are nearly so in the Camelidee, Camelojpardalis, 

 Dicotyles, and Bos. 



Between the above-described fissure and the fissure of Sylvius there are, on the right 

 side of my specimen, only transverse twisted convolutions of considerable length, five or 

 more in number, according to the way in which they are counted. On the left side an 

 irregular longitudinal and fairly lengthy suprasylvian fissure exists, nearer the sylvian 

 than the lateral fissure, and therefore quite lateral in position, with several smaller sulci 

 joining it. Having the typical Artiodactylate brain before us, it is possible to recognize 

 among these the descending {ssd), posterior {ssp), anterior (ss«), and superior {sss) 

 branches of the main fissure, the first mentioned (if correctly identified) running in the 

 direction so characteristic of the true Swine. 



The anterior branch of the suprasylvian fissure has no connexion with the coronal 

 fissure. It ends independently, much as in the Cavicornia and Swine, with a downward 

 tendency ; nevertheless I am not able to recognize any thing corresponding to the 

 wedge-shaped convolution formed between it and the insignificant superior limb of the 

 same fissure, so well marked in the Swine, as above described. 



The fissura splenialis does not curve upwards anteriorly to become superficial, as it 

 does in Sus, but continues onwards to blend with the fissura genualis, at the same time 

 that it sends up a short perpendicular fissure about one third from the anterior extremity 

 of the hemisphere, just long enough to be seen upon the surface. There is a short 

 vertical sulcus, generally more or less developed in the Ungulata, to be noticed, sepa- 

 rating the posterior limb of the splenial fissure from the corpus callosum, nearer the 

 latter than the former in the present case. 



The sylvian fissure is insignificant, the fissura rhinalis being continuous with it before 

 and behind. 



The small size of the optic and the olfactory nerves, and the not great development 

 of the corpora quadrigemiua, are sufficiently emphasized by Gratiolet to require no fur- 

 ther mention. 



If the view here adopted is not the correct one, and what is above described as the 

 lateral fissure is the suprasylvian, then the brain of the Hippopotamus difiers from that 

 of all allied forms in the immense breadth of the interval between the sylvian and the 

 suprasylvian fissures, a breadth not to be explained upon any known hypothesis, and 

 opposed by what is found in Hippopotamus liberiensis. There are no analogies, also, 

 in favour of what would then be the correspondingly peculiar narrow interval between 

 the splenial and suprasylvian fissures. 



