OSTRACODA. 427 



pose. Iii 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 deferens 

 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 receptacula 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 Gypridinq, 

 carry about with them between the shell valves until the young are 

 hatched. The free development of C;/prls consists of a complicated 

 metamorphosis. The larva;, 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 young larva of 



Numerous fossil forms are known from "'* * aup " us sta " e ' with 



three pairs of appendages. 



almost all formations, but, unfortunately, J/, stomach; z>, intestine;. 

 only the remains of their shells are pre- S2f ' she11 7 sck ; ; A> ' A " "* 



J and second antenna?; -3ft'/, 



served. mandible. 



Oypridina-. 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 strung seta?, aud have olfactory hairs at their 

 extremity. The posterior antennas are biramous swimming feet. The biting 

 part of the mandible is weak HI- entirely aborted ; palp is five-jointed, pediform. 

 and of considerable length. The seventh pair of appendages is represented by 

 a cylindrical ringed appendage (Putzfus>). ('//jn-iiJiini ini'difrrri/ n<n ('o>t:i. 

 AstcrojH- nl>hi Hi/a dr.. Trieste. Ilt/Juri/^rix Dana. 



Cythcre 0. Fr. Mlill. Without heart. The anterior antennie are bent at 

 their base and beset with short seta?. The posterior antennae are strongly 

 developed, with hooks on the terminal joint. Three pairs of legs, of which the 

 last is the most strongly developed. The abdomen lias only the caudal fork, of 

 which the two branches are small and lobe-like. The testes and ovaries do not 

 project between the lamella 1 of the carapace. The male genital apparatus has 

 no mucous gland. They are all marine animals. The females often carrv the 



