GENERATIVE ORGANS OF ARTHROPODA. 297 



is formed in consequence of it, calls to mind tlie similar relations of 

 parts in tlie Branchiata, and notably in tlie Poecilopoda. 



The ovaries in the Scorpionea are formed of three long tubes 

 which bend towards, and pass into, one another at their hinder ends, 

 while they are also connected with one another by four ti'ansverse 

 anastomoses ; in the walls of these tubes, which often form tubular 

 diverticula, the ova are formed. The segmented character of the 

 organ is implied by the transverse connections, which form four 

 wide meshes on either side, for these segments have exactly the 

 same position as those of the abdomen. Spindle-shaped and 

 widened oviducts are continued on from the two outer longitudinal 

 tubes, which function as receptacula seminis for the sperm which 

 they receive; they open at the base of the abdomen. 



The testes also of the Scorpionea are a pair of winding canals, 

 united by transverse commissures. Their double character is implied 

 by the presence of two tubes on either side. The vas deferens of 

 each testis opens to the exterior, after uniting with its fellow of the 

 opposite side at just the same point as that occupied by the genera- 

 tive orifice of the female. In addition to the vas deferens there are 

 accessory organs on either side, which as a rule have the form of 

 two pairs of caecal tubes, which vary in length and function partly 

 as glands, and partly as seminal vesicles. 



The separation of the germinal glands of either side is complete 

 in the Galeodea and male Aranea. The ovaries are two tubes, 

 on the outer surface of which the ova are developed; in the 

 Spiders they are developed on stalked processes. In some (Segestria, 

 Oletera) the ovaries are represented by a closed ring. A vaginal 

 canal, which is sometimes widened out (Galeodes), is formed from the 

 union of the two ovarian tubes, which serve to carry the ova out- 

 wards; this canal has one or two seminal vesicles at its termination. 

 These are found also in the Aranea, where they often open inde- 

 pendently in front of the orifice of the vagina. The male organs 

 in the Graleodea may be derived from those of the Scorpionea, by 

 supposing that the transverse anastomoses between the longitudinal 

 trunks have disappeared. Finally, in the Aranea, these longitudinal 

 tubes are reduced to two. 



Bertkau, Ueber d. Generat.-Apparatus. Araueicleu. Arch, f. Nat, 1875. 



§ 231. 



In the Opilionida and Acai-ina the circular form of germinal 

 gland is the dominant and general arrangement ; it is derived from 

 the transverse connection of the ovaries, which is seen in ^ the 

 Scorpionea, The unpaired stage of the germinal gland, which is to 

 be regarded as the more primitive one, is implied by this arrange- 

 ment. This circular form is most pei-fect in the Opilionida (Fig, 

 156, B o). Just as in the Aranea and Scorpionea the ova are formed 

 in stalked diverticula on the surface of the ring, whence they pass 



