T5T WILLIAM A. UASWELL M.A., 15. SC. 211 



the weather being* hot, the brain was far from being in a good 

 state of preservation ; but as the opportunity of procuring tlio 

 brain of one of those sharks does not often occur, and as it 

 presents some marked peculiarities, tliese imperfect notes and 

 drawings may be of some interest. 



The cerebrum is somewhat heart-shaped, much broader in 

 front than behind, and considerably broader than long. It does 

 not display a marked division into lobes, a shallow depression 

 alone separating the two halves. The ihalamencephalon is 

 almost entirely covered by the cerebellum, very little of it being 

 visible when the brain is looked at from above. The cerehellam 

 {middle-brain of Miklouho-Maclay) is not very largely developed. 

 In front it overlaps the thalamencephalon, but behind it does 

 not in any way overlie the commencement of the fourth ventricle. 

 It is nearly symmetrical, and is divided into two principal parts 

 b\^ a transverse fissure, each of the two lobes thus formed beino* 

 similarly subdivided into several lobules. The corpora restiformia 

 are remarkably simple ; owing to the state of the specimen, I 

 could not attempt to reproduce the arrangement of the convolu- 

 tions in detail. The medulla oblongata is remarkable for its 

 extreme length, being nearly as long as the whole of the 

 remainder of the brain. 



I have not yet had the opportunity of comparing the brain of 

 this shark with that of other Selacliii more nearly allied to it 

 than Cheiloscij Ilium, but on comparing it with Miklouho-Maclay's 

 figure and description of the brain of Carcharius,'-'- which is 

 regarded as an allied genus, it presents some marked differences 

 of which the chief are the smallness of the cerebellum, the great 

 breadth of the cerebrum (though, it should be added, this feature 

 may have been somewhat exaggerated by the condition of the 

 specimen), and more particularly the remarkable length of the 

 medulla oblongata. 



*Beitr iige zur Verg-leichenden Neurologie tier Wirbeltliicre, i., p. 24, pi. vi., 

 fitr. 1. 



