CRUSTACEA— SEXUAL ORGANS 



373 



Copepoda.— The germ glands are mostly unpaired, and placed symmetrically in the 

 anterior trunk segment dorsally on the intestine. That they were originally double 

 is occasionally apparent. In many parasitic Copepoda (Fig. 247) the germ glands are 

 distinctly paii'ed and not connected by any transverse bridge. In Sapphiriiia a 

 transverse bridge occm-s. The oviducts are paired, and generally branched. Their 

 ends are glandular or jirovided with glandular invaginations (cement glands), whose 

 secretion yields the material for the egg s&cs. A receptaculum seminis common to 

 the two oviducts is often found. The paired apertures lie in the first abdominal 

 segment (sometimes at its posterior 

 edge) either ventrally, laterally, or 

 (rarely) dorsally. The sperm passages 

 are paired or unpaired ; in the latter 

 case they are generally on one side. 

 They are provided with a glandular 

 division, which yields the envelope of 

 the spermatophore, and often with a 

 wider portion functioning as spermato- 

 phore pouch. The apertures in the 

 genital segment are paired or unpaired ; 

 in the second case frequently asym- 

 metrical. 



Argulidse. — Two pairs of testes 

 occur in the caudal fin, and there are 

 2 vasa deferentia with common sperm 

 vesicle. A glandular tube, coming 

 from the anterior part of the body, 

 enters each vas deferens. The two 

 vasa deferentia unite under the intes- 

 tine into a common ductus ejacula- 

 torius, which opens at the end of the 

 last thoracic segment on a papilla-like 

 projection. The ovary is unpaired, 

 and even from its first appearance 

 asymmetrical ; it lies in the thorax. 

 The oviduct first appears paii'ed, but 

 it is afterwards atrophied on one side, 

 and emerges at the base of the caudal 

 fin. Two receptacula seminis, entirely 

 separate from the female genital appar- 

 atus occur on the under side of the 

 caudal fin. 



Cirripedia. — The strikingly lobate 

 ovaries are paired in the Balanidce, 

 and lie deep down in the shell ring 

 (Fig. 207, p. 304) in that part of the 

 body cavity which extends into the 

 mantle fold. In the Lepadidce (Fig. 

 205, p. 303) the ovaries, which are to 

 some extent united, lie in the anterior 



Fig. 248. — Longitudinal section through a 

 mature Sacculina carcini externa, at right angles 

 to the plane of symmetry (after Delage). co, Cloacal 

 aperture ; sjj, sphincter of the cloaca (d) ; g, ganglion ; 

 ai, outer integumental lamella, covering the hrood 

 cavity ; at, female genital atrium, into which the un- 

 paired portion (,uov) of the ovary and the cement 

 glands {cci) enter ; Wt, brood cavity, sho^vn empty to 

 the left, with egg sacs (es) containing the developing 

 eggs to the right ; pov, the paired part of the ovary ; 

 u, inner integumental lamella covering the body 

 proper or visceral sac ; p, stalk entering the aperture 

 in the shell carapace (cp) of the host ; w, attachments 

 of the roots on the stalk ; da, central lacuna of the 

 stalk continued into the lacunas of the outer integu- 

 mental lamella, the roots, etc., representing the body 

 cavity ; t, testes. 



cephalic portion of the body called 



the peduncle. In both the Balanidce and the Lepadidce the terminal division of the 



oviduct emerges on a projection on the basal joint of the anterior pair of tendril-like 



