590 Chronicles of Science. : [Oct., 
line in the transverse section of the hair, whilst the Semitic have a 
more or less angular outline. 
Formation of Coral Reefs.—Dr. Carl Semper, who has resided 
some years in the Philippines and is a most accomplished naturalist, 
has brought forward some objections to Darwin’s theory that atolls 
and barrier reefs imply the gradual sinking of a continent or island, 
whilst coast reefs necessitate an elevation of its shores. Darwin 
himself, with his true honesty, mentioned some difficulties to the 
theory, and Dr. Semper now quotes some observations of islands near 
the Philippines which certainly do not accord with Darwin’s theory. 
He describes a horizontal surface of colossal dimensions, which 
could not possibly be formed during a depression which a few miles 
farther north had produced a channel of 70 fathoms in depth. He — 
rather regards the physical influences, especially the internal sea- 
currents caused by the rain, and the exterior direct and diverted 
ones, as the cause which have produced in the north of this district 
atolls, and in the south the coast reefs, simultaneously with an 
elevation. Whilst in the south the deep-going eroding action of the 
wave-blow or the wash of the sea, has gradually planed away the 
dense and solid coralline limestone to a nearly horizontal surface, 
which lies at about the depth to which the sea-wash is capable of 
acting ; in the north, the becks coming down from the mountains 
conjointly with the wash and currents of the sea, have acted much 
more strongly upon the soft readily decomposable basalt of the west, 
than was the case with the limestone of the south, and thus has 
arisen the apparently incompatible conditions of their respective 
coral growths. 
A natural Hybrid-Barnacle—Dr. Fritz Miller, of Desterro, 
in South America, one of the most able of Mr. Darwin’s champions, 
recently directed his attention to the Barnacles occurring on that 
coast. He found a species of Sea-acorn (Balanus) which either 
attaches itself to, or becomes overgrown by various forms of sponge, 
and it was observed that the third pair of legs or cirri were equipped 
with numerous teeth, whence he terms it B. armatus. He de- 
scribes a very remarkable grouping of different species of Balani 
on a rock, according to depth. The sensitiveness of these animals 
to luminous impressions is not, he says, dependent on the eyes dis- 
covered by Leidy. He took a large Balanus tintinnabulum living, 
out of its shell and separated it from the operculum, with which the 
eyes remained in connection. It lay in a saucer of water, with its 
cirri half unrolled. As often as the shadow of the hand fell upon 
it, it rolled up the cirri with a sudden movement. In B. tintinna- 
bulum the eyes are very distinct; in B. armatus they have not yet 
been found. The most interesting observation of Dr. Miiller’s is, 
however, the existence of a natural hybrid between B. armatus and 
B. assimilis which he most minutely describes, and for the existence 
