592 PHILOSOPHY OF ZOOI,OGY. 



the tubular appendage, and opens by a small pore at 

 its extremity. This aperture Cuvier regards as simple, 

 but Ellis observes of the whole, " it is of a tubu- 

 lar figure, transparent, composed of rings lessening gra^ 

 dually to the extremity, where it is surrounded with a 

 circle of small bristles, which likewise are moveable at the 

 will of the animal. These, with other small hairs on the 

 trunk, disappear when it dies.*" There is probably no 

 union of individuals, each being a perfect hermaphrodite. 



The spawn of the Lepas fascicularis is a spongy body, 

 and adlieres to fuci, feathers, or other bodies, with which it 

 accidentally comes in contact. The rapidity of growth, af- 

 ter hatching, is truly astonishing. The spawn of full 

 sized individuals, springing from spawn which has been 

 deposited on a feather, (as I have stated in the Memoirs 

 of the Wernerian Society, vol. ii. p. 243.), A^^ll become 

 unfolded, and attain maturity, before the feather itself be- 

 gins to exhibit any symptoms of decay. A ship's bottom 

 comes covered with other species in a few months. 



The animals of this class are all inhabitants of the sea. 

 Many of them are attached to floating wood, and others to 

 the skin of marine animals, so that they enjoy all the ad- 

 vantages of locomotion, without the exercise of the exertion 

 requisite for its production. Their remains are seldom 

 found in a fossil state. Some of the species have been 

 used as food. In taking a view of the genera we shall dis- 

 tribute them, after the manner of Ellis, Phil. Trans. 

 vol. i. p. 848, into pedunculated and sessile. 



Tribe I. — Pedunculated. 



The essential character of this tribe consists in the body 

 being supported by a peduncle, the lower part of which is 

 permanently fixed to other bodies. 



