290 MORPHOLOGY OF THE CEREBRAL CONVOLUTIONS. 



as found in the brain of Man to distinguish it from the conditions as found in the 

 Simiadse, I have occasionally found in the negro brain that it was entirely invisible 

 superficially or at most presented the appearance as seen in the chimpanzee, Plate 

 XXXIX, fig. 3, showing in this respect the nearer relation of the negro than the 

 white brain to the simian type. Indeed, there is not one of all the points which 

 have been asserted to be characteristic of the convolutions of the human as distin- 

 guished from the ape brain which the study of the negro brain will not show to 

 be entirely relative. Many of these points will be indicated hereafter, and the 

 author firmly believes that had the negro brain been utilized by previous investi- 

 gators in elucidating the relations of the human to the simian type, many mistakes 

 would have been avoided, especially in the comparison of the occipital lobes. 



Posteriorly the calcarine fissure proceeds directly backward to the extremity 

 of the hemisphere. It is straight, or nearly so, in the monkeys and apes, but in 

 Man it becomes more or less curved with the convexity directed upwards, Plates 

 XLII and XLIV, fig. 2. In the brain of A teles, Plate XXXVII, fig. 17, this curve 

 is also found to a slight extent. In Chrysothrix, Plate XXXVIII, fig. 8, it curves 

 slightly downward. It ends in an expanded cleft or transverse fissure, one branch 

 ascending and the other descending. For this I propose the name of transverse 

 calcarine, fissura calcarina transversus, t. ca., figures of Plates XXXVII and 

 XXXVIII. With regard to this fissure I have observed some interesting de- 

 velopments in the brain of Man. In all of the Simiadae the tranverse is continuous 

 with the horizontal portion of the fissura calcarina, but in Man a bridging convolu- 

 tion is often found separating it from this in such a manner that the transverse 

 calcarine may be pushed so far backward as to make its appearance upon the lateral 

 surface of the apex of the occipital lobe. This is the case in Plate XXXVI, fig. 6, 

 and in Plate XLIV, fig. 1, where the end of the calcarine, ca, is seen separated from 

 the transverse calcarine, t. ca, which now appears apparently as a fissure of the lateral 

 surface and as such has been described by several writers, thus leading to consider- 

 able confusion. By comparing the mesial surface of same hemisphere, Plate XLIV, 

 fig. 2, the calcarine, ca, may be seen running around the extremity of the occipital 

 lobe and a tendency to a vegetative repetition, as I consider it, of the transverse 

 calcarine has made its appearance, the sulcus calcarina transversus, (see classifica- 

 tion of fissures). 



On Plate XLI, fig. 2, the transverse calcarine is seen situated some distance 

 from the extremity of the occipital lobe and a bridging convolution may be seen com- 

 pletely separating it from the calcarine. On Plate XLIII. fig. 3, a bridging convolu- 

 tion is seen curving backward and downward from the apex of the cuneus, giving 

 this brain a peculiar aspect in this region. In the other hemisphere of this brain, 

 fig. 4, this bridging convolution is not present, but its place is taken by one situated 

 more posteriorly. 



In the brain of a Chinaman, Plate XLI, figs. 5 and 6, in both the right and 

 left hemisphere we have a bridging convolution well developed, giving quite an 

 unusual appearance to this portion of the brain as found in the white race. I pro- 



