. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. OSTEACODA. 427 pose. In addition a large copulatory organ, which may be derived from a modified pair of appendages and often possesses a very compli- cated structure, is always present. The male genital organs consist on either side of several elongated or globular testes, of a vas def erens and the copulatory organ ; the presence in Cypris of a very peculiar paired mucous gland and the size and form of the spermatozoa seem to be worthy of notice (Zenker). The female of Cypris possesses two
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. OSTEACODA. 427 pose. In addition a large copulatory organ, which may be derived from a modified pair of appendages and often possesses a very compli- cated structure, is always present. The male genital organs consist on either side of several elongated or globular testes, of a vas def erens and the copulatory organ ; the presence in Cypris of a very peculiar paired mucous gland and the size and form of the spermatozoa seem to be worthy of notice (Zenker). The female of Cypris possesses two ovarian tubes which project into the reduplicature of the carapace, two receptaoula seminis, and the same number of genital openings at the base of the abdomen. Development.—The greater number of Ostracoda lays eggs, which they either attach to water-plants (Cypris}, or, as in Cypridina, carry about with them between the shell valves until the young are hatched. The free development of Cypris consists of a complicated metamorphosis. The larvae, when hatched, possess, like the Nauplius form, only three pairs of appendages, but are strongly compressed laterally, and are already enclosed in a thin bivalve shell (fig. 338). In the marine Ostracoda the development is simplified, so that the metamorphosis is entirely absent. The Ostracoda feed altogether on ani- mal matter, as it seems especially on the carcasses of different aquatic animals. FIG. 338.—Very youn;? larva of Numerous fossil forms are known from ^)n>- N'mpUtM stage, with three fairs of appendages. almost all formations, but, unfortunately, M, stomach; D, intestine; only the remains of their shells are pre- ££ ££j^f' ** served. mandible. Cypridina. "With heart and large movable paired eye. With deep excava- tion in the edges of the shell for the passage of the antennae. The anterior antennas are bent, furnished with strong seta:, and have olfactory hairs at their extremity. The posterior antenna; are bir
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