1865.] 



Notes and Correspondence. 



565 



series. The characters of an elevated 

 brain are : 1st, the large size of the 

 frontal lobe, particularly of its 

 superior portion ; 2nd, the large 

 size of the lobule of the second 

 ascending convolution, and the 

 simultaneous development of all 

 the external connecting convolu- 

 tions; also the reduction of the 

 ascending roots of the ascending 

 convolutions : and the diminution of 

 the ascending branch of the curved 

 convolution. The small size of the 

 occipital lobe and of the marginal 

 convolutions are in all monkeys to 

 be regarded as signs of elevation. 



With regard to the lateral ven- 

 tricles, I may observe that by care- 

 fully removing the brain tissue they 

 were exposed (as in Fig. 3) ; both an- 

 terior and posterior cornu were well 

 developed, and the hippocampus 

 major a was sufficiently obvious, 

 while a small protuberance on the 

 inner wall of the posterior cornu 

 was noted, which may undoubtedly 

 be regarded as the homologue of 

 the much canvassed hippocampus 

 minor. The ventricles were shal- 



lower, and their parts less defined 

 than in higher monkeys, but it 



FIG. 3 



was not difficult to ascertain the 

 homologous parts. 



E. Ray Lankester, 

 Downing College, Cambridge, 

 June, 1865. 



The SaJiara and 



the North-East Trade. Wind. 

 F.R.S., F.G.S., &c. 



By W. Pengellt, 



The exigencies of time and space 

 forbid me, on the present occasion, 

 to take up all the questions raised 

 by the Rev. H. J. Ward's note " On 

 the Connection between the sup- 

 posed Inland Sea of the Sahara and 

 the Glacial Epoch," which appeared 

 in the last (the April) Number of 

 the ' Quarterly Journal of Science.' 

 There is one point, however, to 

 which I may be permitted to call 

 attention. Mr. Ward believes that 

 to the question " What causes the 

 N.E. Trade-wind?" most geogra- 

 phers will reply without hesitation, 

 "Mainly the Sahara" (p. 357).— 

 Again, he says, at p. 358, " Suppose 

 the Sahara then, to be an expanse, 

 not of sand, as now, but, as formerly. 

 of water ; what would be the re- 

 sults? * * * * * 



The trade-wind would cease, or be 

 so reduced in strength as to exert 

 but slight pressure on the surface 

 of the Atlantic." 



Let it be granted that the Sahara 

 is more heated than the land and 

 water surrounding and near it ; it 

 will follow that its atmosphere will 

 be expanded, diminished in weight, 

 will ascend, and thereby produce a 

 vacuum, into which, under normal 

 conditions, the air from all sides 

 will flow. That on its eastern mar- 

 gin will acquire an apparently west- 

 erly motion, and that on the west 

 will move in a relatively easterly 

 direction ; — correctly, the easterly 

 motion which the atmosphere pos- 

 sesses in consequence of the earth's 

 rotation will be diminished in the 

 first case and augmented in the se- 



