GENERATIVE ORGANS OE ARTHROPODA. 



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a ceecal uterus which is continuous with the duct. At their hinder end 

 they seud off a short duct (od) to the generative pore. The organs 

 of either side are united in the same way in the testis. This is 

 formed of a double row of glandular follicles, which unite into a 

 coiled canal, which forms the simple excretory duct and opens at the 

 base of the last pair of feet. 



The generative organs of the Decapoda resemble those of Mysis, 

 by being similarly connected in the middle line ; they appear to be 

 further developed by various 

 differentiations. The female A 



organs are formed by two 

 long tubes which run for- 

 wards and backwards, and 

 are united transversely with 

 one another; these tubes 

 function partly as germinal 

 glands, but chiefly as ovi- 

 duct and uterus. In the 

 Crayfish the two anterior 

 divisions have the form of 

 short lobes, while the two 

 hinder ones are fused into 

 an unpaired piece. On each 

 side a short duct passes to 

 the genital pore, which in 

 the Caridina has the same 

 position as in the Schizo- 

 poda; in the Macrura it is 

 placed on the basal joints 

 of the third pair of feet, 

 but in the Brachyura on 

 the segment of the body, 

 which carries this pair. The Brachyura are also distinguished by a 

 pouch-like enlargement of the oviduct (seminal pouch). In the 

 male appai'atus the testes are formed by two much-coiled tubes, 

 which are transversely connected with one another in front, and 

 which, like the female organs, lie for the most part in the cephalo- 

 thorax; in Pagurus only are they placed in the abdomen. In the 

 latter they give off two long and closely-coiled but gradually-widen- 

 ing ducts. Herein they agree with most of the Decapoda, but they 

 are distinguished from them partly by the increased size of the 

 lobes formed by the coils of the seminal canal, and partly also by 

 the formation of the unpaired piece, which unites the glands of 

 either side. The germinal glands are more completely united in 

 Astacus. A vas deferens with long coils passes on each side to the 

 outer generative orifice, which is placed, as a rule, on the basal joint 

 of the last pair of feet ; in the Brachyura, however, it is found at 

 the end of a penis, which is formed by a metamorphosed appen- 

 dage. The opening of the male apparatus only is then the same 



Fig. 155. 



Homarus. 

 deferens. 



Male generative organs. A Of 



BOfOniscus. tt Testes, vd Vas 



vs Seminal vesicle. o Its orifice. 

 p Copulatory organs. 



