CRUSTACEANS. 609 
the stomach. These tubular glands are generally divided at the 
end near the mouth into a few blunt branches. Their precise 
connexion with the two main ducts has not been discovered. The 
state of these two masses varied much—but since, at times, they 
contained aggregations of matter consisting of little balls closely 
reseinbling, in general appearance and size, the ovigerms with their 
germinal vesicles and spots, there could be no doubt that they are 
ovaria. DARWIN was unable to discover the orifice by which Sv. 
ANGE supposes the ova to enter the sac. His observations lead 
him to believe that the mode by which they enter the sac is quite 
different: ‘‘Immediately before one of the periods of exuviation, 
the ova burst from the ovarian tubes in the peduncle and round the 
sac, and, carried along the circulatory channels, are collected beneath 
the chitine-tunic of the sac, in the corium, at this period remarkably 
spongy and full of cavities. The corium then forms, or rather, (as 
Darwin believes,) resolves itself into a delicate membrane envelop- 
ing each ovum and uniting them together in lamelle; the corium, 
having thus far retreated, then forms under the lamelle the chitine- 
tunic of the sac, and the last-formed one is immediately moulted 
with the other integuments of the body. The membranes harden, 
the lamelle of ova become detached from the bottom of the sac, 
and are attached to the ovigerous frena.’’ In the Balanoidea the 
branching and inosculating ovarian cceca form a layer covering in 
part the basis of the balanus, and in certain cases extending upwards 
between the two layers of corium round the walls of the shell!.] 
The testes lie on the sides of the body as small blind sacs that are 
attached to branches that coalesce to form larger stems like veins. 
On each side there arises from the union of these branches a wide 
and tortuous canal (vas deferens), which afterwards becoming nar- 
rower advances towards that of the opposite side; thus these two 
tubes lie close together at the base of the caudiform appendage of the 
body, where they unite to form a ductus ejaculatorius, which opens at 
the apex of the appendage *. In some lower crustaceans the females 
are much more numerous than the males, which are only imperfectly 
1 Darwin Lepadide, pp. 56—60, and Monogr. of the Balanide, London, 1854, 
p- 100. 
2 WaGNER in MUELLER’S Archiv, 1834, s. 467—473, Tab. vin. figs. 8—rt, 13; 
Martin St. ANGE Mém. sur organisation des Cirripédes. Paris, 1835, 4to. pp. 2o— 
22, Pl. 1. figs. 4—7. 
VOL. I. 39 
