296 COMPARATIVE ANATOMY. 



as in the Schizopoda, while the female orifice is placed farther 

 forwards. 



In the generative apparatus of the Stomapoda the testis com- 

 mences as a fine unpaired tube in the middle line of the caudal fin ; 

 it is continued forwards into a paired tract, from which a much- 

 coiled vas deferens arises. Each of these passes to a penis, which 

 springs from the coxa of the last thoracic foot. An unpaired gland, 

 which begins in the cephalothorax, opens at the same point. The 

 ovary passes backwards as an azygos, and afterwards as a paired, 

 gland, as far as the cephalothorax. Each gives off an oviduct in the 

 third thoracic segment, which opens at the base of a pouch placed in 

 the middle line. The Decapod-type prevails in them, though 

 modified in the female by the approximation of the orifices. 



In the Pcecilopoda we see a combination of the two forms repre- 

 sented in the Crustacea. One form is followed in the median con- 

 nection of the organs of either side, and the other in the large 

 number of germ-sacs formed by the fine terminal branches of the 

 network, which makes up the generative organs. The wider tracts 

 serve as efferent passages, which are considerably widened in the 

 female so as to collect the eggs, and are continued into the efferent 

 duct on each side. 



§ 229. 



A lower stage is seen in the female apparatus of the Protracheata. 

 The ovary is a body divided into two halves by a septum, and 

 sends off a paired oviduct; this passes forwards as a coiled tube, 

 and then bends round to a widened portion, which functions as a 

 uterus. These canals are continued backwards, and only unite to 

 form a common short vagina near the generative pore. 



In the male apparatus the testes are completely separated from 

 one another ; each of them is provided with a glandular appendage, 

 and is continued into a long looped vas deferens. A common ductus 

 ejaculatorius, which also opens at the hinder end of the body, is 

 formed by the union of the two efferent ducts. 



§ 230. 



The two kinds of generative glands in the Arachnida are, as a 

 rule, unpaired; when paired they are connected transversely, and 

 open either by one or two ducts anteriorly, and on the ventral 

 surface. In addition to accessory glandular organs, or special 

 enlargements of the excretory ducts serving for the storage and 

 reception of the sperm-masses or ova, there arc external organs 

 which carry the sexual products outwards, and which are called 

 penes or vagina) according to the sex. The male organs repeat with 

 slight variations the type of the female. The union of the genital 

 glands of either side and the azygos portion of the apparatus which 



