316 



PARASITIC WORMS. 



The excretory system consists of the usual two pairs of 

 longitudinal vessels, both lying in almost the same horizontal 



Fig. 8. Chitinolepis mjobrrgi. .4, semi -diagrammatic representation 

 of three mature segments in ventral view, from a whole preparation; 

 c-s, cirrus-sac; o. ovary: t, testes; v, yolk-gland; vag, vagina; B, an egg. 



plane. Those which must be regarded as the ventral vessels are 

 slightly wider than tlie otliers, and connected by narrow trans- 

 verse intersegmental vessels. The genital pores are unilate- 

 ral, on what appears to l^e the right side of the strobila. The 

 genital ducts pass dorsally to both the longitudinal excretory 

 vessels and to the longitudinal nerve of that side. The cirrus- 

 sac is elongated and spindle-shaped, extending inwards a little 

 beyond the nerve of the side. It measures 0.34—0.37 mm. 

 in length, and has a maxunum thickness of 0.40—0.06 mm., 

 according to its state of contraction. It contains a long 

 internal vesicula seiuinalis. There is also, connected with its 

 inner end by a nari-ow duct, a pear-shaped external vesicula 

 seminalis which, when full of spermatozoa, measures about 

 0.15 X 0.055 mm. The cylindrical cirrus is armed with 

 minute spines. The vagina opens ventrally to the cirrus-sac. 



