GOt) Mr. 1\. J. Oiilo|)|) on a 7iew 



dorsal and ventral surfaces of the middle third of the se<;- 

 nient, in which all the genital organs are contined. Dorso- 

 ventral muscles were not observed. 



(b) Excretory Sijslem. — The excretory system consists of 

 two longitudinal vessels, dorsal and ventral, on cither side 

 towards the lateral margins of the segments, lu the head 

 region the corresponding vessels from each side unite and 

 form a loop l)ctweeu the suckers. The ventral exci'ctory 

 vessels are large and thiu-walled ; they are more or less 

 circular in transverse section, with a diameter of about llO/u. 

 in mature segments. In the hinder end of each segment a 

 transverse duct, 25 /i in diameter, connects the ventral 

 vessels. The dorsal excretory vessels are much smaller, but 



Fig. 3. 



UK 



^ L_u • ■ - 



1 • I I J. I I I I \ ^.-^ 



Transverse section of portion of mature segment, reconstructed 

 from serial sections. 



C.P. = cirrus-pouch ; D.E. C. — dorsal excretory canal ; L.3I. = longitudinal 

 muscle-layer ; N. C. = nerve-cord ; ()o. = ovary ; U.S. = recepta- 

 culumseminis; <S'. 6'. = ^^11 ell-gland; 7'. = testis; 7'.3/. = transverse 

 muscle-layer; 7X<7. = V)igina; 7'.7>. = vas deferens; V.E.C.= 

 ventral excretory canal; ;}'.6'. = yolk-glaiid. 



have a thicker and slightly muscular wall ; they are situated 

 at about the level of the dorsal margin of the ventral vessel, 

 but more towards the interior of the segment. In transverse 

 section they are circular with a diameter of 15 /x. Like the 

 ventral vessels they also are connected to each other by 

 transverse vessels, situated one at the hinder end of each 

 segment, and running parallel to, but dorsal of, those con- 

 necting the ventral vessels. Towards the posterior end of 

 the strobila the lumen of the dorsal vessels may increase in 

 diameter, so that in ripe segments they may attain about 

 half the diameter of the ventral vessels. 



(c) Nervous Si/stem. — The nervous system consists of two 

 well-developed lateral nerve-trunks. In general, the poral 



