Introduction to Animal Aforpholo^y. 369 



strands. The material is extruded suddenly and in 

 large quantity, especially when the female lays 

 eggs ; the material is arranged by the comb-like 

 claws. 



All but Tardigrades are dioecious ; the testes are 

 single or clustered caeca. The vasa deferentia open 

 far from the anus, at the base of the abdomen, between 

 the stigmata, and in this bilateral termination they 

 resemble the Chilognaths. Accessory saccular glands 

 secrete the adhesive material which makes sperma- 

 phores. The only intromittent organs are the wart- 

 like processes in Scorpions, the protrusible penis of 

 (Phalangium), which corresponds to the ovipositor of 

 the female, and has two large branching bristles at 

 its end, the double spiculum of Pentastoma, or the 

 single one of some mites. In male spiders the spoon 

 shaped last joint of the maxillary palp places the 

 spermaphores in the female vulva. The ovary is tubu- 

 lar, with grape-like eggs on a central rachis, or rarely 

 in a ring round it (Phalangium, some Mites). In 

 Scorpions (which, like Phrynus, are oviparous) the 

 ovary consists of three azygous communicating tubes. 

 In Phalangium the two oviducts unite, and a duct 

 passes to the protrusible ovipositor ; a similar organ 

 present in some Mites. Parthenogenesis is described 

 in Cheiletus. Tardigrades have a median epi-intestinal 

 ovary, two lateral testes, each with one vas deferens 

 and a common receptaculum seminis. In Galeodes 

 there are two ovaries, as in Spiders. Many Mites 

 have an imperfectly annular ovary, and Pentastoma 

 has a long ovary ending in two oviducts united by an 

 annular canal. From thence comes a single canal 

 dilated into a uterus, which ends at the vulva. Where 



2 B 



