432 



ARACHNIDA — CHERNETIDEA 



are eleven in number (except in Chiridmm, which has only ten), 



and are frequently bisected by a median dorsal membranous line. 



There are nine ventral plates. There is a membranous interval 



down each side between the dorsal 

 and ventral series of plates. 



The chitinous membrane between 

 the plates is very extensible, render- 

 ing measurements of the body in 

 these animals of little value. In 

 a female full of eggs the dorsal plates 

 may be separated by a considerable 

 interval, while after egg-laying they 

 may actually overlap. The four 

 stigmata are not situated on the 

 plates, but ventro- laterally, at the 

 level of the hinder borders of the 

 first and second abdominal plates. 



The first ventral abdominal plate 

 bears the genital orifice. In the 



Fig. 222.— a, Oiernes sp., diagram- same plate there are two other orifices, 



matic ventral view, x about 12. 

 u, Anus ; ch, chelicera ; g, gener- 

 ative opening ; p, pedipalp ; 1, 

 2, 3, 4, legs. (Tlie stigmata are 

 at the postero-lateral margins of 

 the 1st and 2nd abdominal seg- 

 ments.) B, Tarsus, with claws 

 and sucking disc. 



an anterior and a posterior, which 

 belong to the " abdominal glands." 

 They were taken by some authors 

 for the spinning organs, but their 

 function is probably to supply 

 material for the capsule by which 



the eggs are suspended from the body of the mother (see p. 434). 

 The Chernetidea possess chelicerae, pedipalpi, and four pairs 



of ambulatory legs, all articulated to 



the cephalothorax. 



The chehcerae are two-jointed, the 



upper portion of the first joint being 



produced forward into a claw, curving 



downward. The second joint is articu- 

 lated beneath the first, and curves 



upward to a point, the appendage being fig. 223.— Chelicera of earj^jiw, 



thus chelate. This second joint, or /■ Flagellum ; g. galea ; s, 

 . . . . serrula. (After Simon. ) 



movable digit, bears, near its extremity, 



the opening of the spinning organ, and is furnished, at all events 



in the Garypinae and Cheliferinae (see p. 437), with a pectinate 



