The Protective Device of an Annelid

Abstract

AMONGST a gathering of small Serpulids, &c., received from Mr. Sinel, of Jersey, I find some interesting little worms related to the Sabellidæ. They build a thin membrane- like tube, about one-seventieth of an inch in diameter, coated externally with flat translucent particles of sand. Its lower end is closed, and embedded in sponge or other growths, but the upper end is free, and, when the head of the inmate is protruded, stands about a quarter of an inch high in the water. On this head are two branchial tufts, each having five branches beset with a double row of long ciliated filaments. When all are fully expanded they curve backwards, and cover an area of about one-tenth of an inch in diameter. The branches decrease in size from the inner to the outer pairs, and at the back of the longest but one in each tuft, near its base, is a chocolate or brown coloured vesicle. The two smallest branches curve backwards round the mouth of the tube, and keep up a constant whipping or flicking motion.