608 CLASS X. 
the first pair of feet; in the long-tailed it is a fissure that extends 
along the entire thorax on each side. The water is expelled, on 
the other hand, along a furrow which opens forwards by the side of 
the mouth. In this canal an oval lamina is situated, which is the 
outermost lobe of the second pair of maxille, and produces by its 
motion a current forwards to force the water out". 
In nearly all crustaceans the two sexes are distinct. In the 
Cirripedia, indeed, formerly counted amongst the Molluscs, the 
male and female sexual organs are united in the same individual?: 
[except in certain genera of the Lepadicea, as [bla and Scalpellum 
Leacu, where there are not only, according to DARWIN, males and 
females distinct, but also the surprising fact of ‘hermaphrodites 
whose masculine efficiency is aided by one or more complemental 
males*,’ often exceedingly minute, and rudimentary in structure, 
which are permanently attached to different parts of the female. ] 
The ovary lies as an apparently granular mass in the pedicle of Ana- 
tifa, and under the microscope is seen to be composed of rounded 
lobes ; a tube which traverses the pedicle and opens into the mantle 
above by a fine aperture on the dorsal surface is the oviduct. Tn 
Balanus the ovary lies in the walls of the mantle. [According to 
DarwIn the female organs consist of true ovaria (salivary glands 
Cuy.) seated on each side near the base of the labrum, of unbranched 
ovarian ducts and of ovarian branching tubes and cceca. In the 
Lepadicea the ovarian tubes branch out in all directions within the 
peduncle, and ova are developed in the footstalks of their branches 
as well as at their ends. ‘Two unbranched tubes enter the body of 
the Cirripede from the peduncle and run into the two true ovaria 
situated at the base of the labrum and resting on the upper edge of 
1 See Minne Epwarps Recherches sur le mécanisme de la respiration chez les Orus- 
tacés. Ann. des Se. nat. 2e Série, Tom. x1. Zoologie, pp. 129—142. 
2 A few years ago GoopsIR described small crustaceans, with five pairs of feet, as 
the males of Balanus. Edinb. new Philos. Journ. xxv. 1843, p. 88, Ann. des. Se. nat. 
gieme Sér. 1. 1844, pp. 107—117. These supposed male individuals present however 
little or no resemblance to the juvenile form of Cirripedes, as we have been taught to 
know them by BURMEISTER. 
3 Darwin Lepadide, 1851, p. 182. Darwin found the animals described by 
GoopDsIR not to be males but females distended with ova. He considers them to be the 
females of the unnamed genus belonging to the family of Loniens, described by Goop- 
sR, which live parasitically within the sac of the Balani. See Darwin Monogr. of 
the Cirripedia, Balanide. London, 1853, p. 271. 
