THE CIRRIPEDIA. 473 



sued. The perfect or fully-developed barnacle or sessile Cirripcde 

 has a mouth almost in the shape of a proboscis, and it is sur- 

 rounded by the usual structures noticed in the Crustacea, but they 

 have been more or less modified in their growth. There is a 

 swollen lip, and palpi are soldered to it ; and there are man- 

 dibles, maxillae, and outer maxillae, which serve as a lower lip. 

 The opening into the gullet is situated between the mandibles, 

 and the oesophagus — or tube leading down to the stomach — is 

 capable of violent swallowing movements, and the small creatures 

 brought within the range of the mouth by the whip-like motion 

 of the fine, hairy, and branched cirri are prevented from escaping 

 by the palpi just mentioned. The mandibles have strong teeth, 

 and their duty appears to be to crush and force anything down 

 the oesophagus after it has been guided towards them by the 

 spiny maxillae. The numerous cirri are jointed, spined, and hairy, 

 and act as arms, although they are legs, so to determine currents 

 in the water, which wash multitudes of small creatures within 

 range of the mouth, and which supply the respiratory appendages 

 with abundance of well aerated fluid. The stomach is curved 

 and bent up, and is provided with glands and branching liver 

 tubes, and is lined with an epithelium ; and small Crustacea, mi- 

 nute Mollusca, and larvae of all kinds are digested by it. When 

 the food has been digested, the internal epithelial coat of the 

 stomach covers it like a bag, and is forced out with it. The eyes 

 in the pedunculated Cirripedia are apparently united ; but two 

 lenses exist, and this double eye is situated deep within the body. 

 It is attached to a muscle at the lowest part of the oesophagus, 

 and lies actually on the upper part of the stomach, so that a ray 

 of light has to pass through many tissues, and to dip down into 

 the body before it can be felt by the optic nerve. Yet these crea- 

 tures are probably sensitive to light. 



The Lepas and barnacle are bi-sexual, and the eggs, when 

 excluded from the body, and to all intents and purposes laid, 

 are collected in leaf-like masses within the sac which lines the 

 shell, and they remain there to be hatched. The leaves of eggs 

 are fertilised when they first enter the sac, and are kept from 

 being washed out by a number of bead-like bodies mounted on 

 stalks, which retain them within a reduplication or fold of the 



