404 



NEUROPTERA 



and placed veiy near the iDrain. 



There are three thoracic and 

 six abdominal ganglia on the 

 ventral chain. The nerves 

 to the wings are connected 

 with the longitudinal com- 

 missures of the ventral chain 

 by peculiar, obliquely-placed, 

 short conxmissures. The repro- 

 ductive glands are peculiar, 

 inasmuch as in each sex 

 the pair of principal glands 

 is connected together in the 

 middle. The testes thus form 

 an arch consisting of a large 

 numlaer of sub-spherical or 

 pear - shaped follicles ; the 

 vasa deferentia are short in 

 Perla maxima, and there are 



Fig. 256. — The iiair of united ovaries of Perla - i • , , , 



maxima: o, egg-tubes; ov, oviduct; r, re- ^^'^ VeSlCUlae seminales ; the 



oeptaculum seminis concealing tire orifice of ejaculatory duct is divided 



the duct and an accessory gland. • j ^ i , 



into three parts by constric- 

 tions. In Ptcnmmrys and in Perla hicaudata, according to 

 Newport and Dufour, the vasa deferentia are very long and 

 tortuous, and there are elongate vesiculae 

 seminales. The arrangement of the ex- 

 tremely numerous egg-tubes is analogous to 

 that of the follicles of the testes, so that, as 

 Dufour says, there is but a single ovary ; 

 connected with the short, unpaired portion of 

 the oviduct, there is a large receptaculum 

 seminis, and near the terminal orifice of 

 the duct there is in F. maxima an eight- 

 lobed accessory gland. 



The eggs are produced by Peiiidae in 

 enormous numbers : the}- are rather small, 

 but peculiar in form, and possess at one 

 extremity a micropyle apparatus, covered 

 by a glassy substance through which Imhof 

 could find no orifice. On the other hand, the chorion on another 

 part of the egg is perforated by several canals. 



Fig. 257. — Egg of Perla 

 maxima. (After Imhof.) 

 c, chorion ; d, oolenm ; 

 ffs, glass-like covering of 

 mioroiiyle apparatus ; I, 

 cavity under same ; g, 

 canals penetrating 

 chorion. 



