CHAP. UIL.] TENERIFFE TO SOMBRERO. 219 
the German Ocean, the temperature of which it lowers sensi- 
bly, and a very narrow belt passing down along the west coasts 
of the British Islands. It is in this belt that we usually work 
the dredge and tow-net; and, with the exception of some very 
curious compound forms which sometimes swarm in the West 
Highland Lochs, Radiolarians are scarce. Whenever the belt of 
water of northern derivation is passed, which is only from sixty 
to eighty miles from the shore, these forms, which frequently 
occur in the Atlantic, the Mediterranean, the Pacific, and all 
moderately warm seas in sufficient numbers to discolor the wa- 
ter, become abundant. The Rapronrarta form a class of the 
somewhat negative subkingdom Prorozoa—a subkingdom re- 
tained for the reception of all those animals of comparatively 
simple structure, such as the Iyrusortra, etc., whose relations we 
can not yet fully make out. The Radiolaria consist essentially 
of a little mass of sarcode, with no very definite bias as to form, 
but tending, when irritated, to assume more or less that of a 
sphere. The sarcode consists usually of rounded or oval gran- 
ular masses of a brownish or yellowish color, interspersed with 
very characteristic round oil-cells, bright yellow, and very re- 
fractive; the whole cemented together by soft transparent sar- 
code, including fine granules. Near the centre of the body 
there is usually a very evident rounded mass of bioplasm 
which colors deeply with carmine; and the same dye brings 
out smaller bioplasts scattered through the general substance. 
When the animal is at rest, and happy in a cell with abun- 
dance of fresh sea-water, soft sarcodic matter from the periph- 
eral layer stretches itself out all round in a maze of straight 
radiating pseudopodia, only visible under a high magnifying 
power; and in these the peculiar flowing motion, which is so 
characteristic of sarcode-feeding filaments, is well marked. In 
many Radiolarians, and especially in some very peculiar com- 
pound forms, a spherical internal chamber, called the “ central 
capsule,” whose function we do not fully understand, is very 
