THE CESTOIDEA 



in 



first, and further back the female system. As the proglottids 

 become mature they drop off in groups. The follicular testes are 

 scattered over the greater part of the dorsal surface (Fig. X.) ; the 

 numerous efferent canals unite to form a larger sperm-duct, which, 

 after an extremely undulating course, enters and traverses the 

 "cirrus pouch," to the muscular walls of which the duct is con- 

 nected by radiating reticular fibres. By the contraction of the 

 wall of the pouch, the sperm-duct is straightened out and the whole 

 cirrus is everted. The germarium is made up of a pair of groups of 

 acini, lying near the ventral surface, and it is noteworthy that, while 

 in the Trematoda the testis is posterior to the germarium, the reverse 



FIG. IX. 



1, 2. Plan of the nervous system of the 

 scolex of Taenia (reconstructed from Niemec's 

 figures). 



1. View from the ventral (or dorsal) surface, 

 a, lateral nerve ; b, one of the two accessory 

 lateral nerves ; c, the ventral (or dorsal) nerves ; 

 d, the ganglionic enlargement of the lateral 

 nerve ; c, the transverse commissure ; /, nerve 

 ring round the rostellum giving off nerves for- 

 wards. Posteriorly it receives eight nerves : g, 

 two nerves to the lateral ganglion ; k, a pair 

 of ventral (and dorsal) nerves ; i, polygonal 

 commissure; j, one of the two ventral (or 

 dorsal) ganglia situated on this polygonal com- 

 missure, and connected to the main transverse 

 commissure by the nerve (I). 



2. Plan of nervous system at the level of 

 the commissure, seen from above, after removal 

 of the "ring." 



3. Diagrammatic transverse section through 

 the hinder margin of a proglottid of Moniezia 

 (somewhat altered from Tower), a, lateral 

 nerve, here dilated to form a ganglion, which 

 is connected with its fellow by a ring-commis- 

 sure, m ; cc', the dorsal and ventral ganglionic 

 swellings at the junction of the dorsal and 

 ventral nerves, with this commissure ; n, a loop 

 round the ventral excretory canal (z). 



holds in the Cestoidea on the assumption that the. scolex is anterior. 

 The vitellarium consists of a vast number of follicles distributed 

 over the ventral, and partially along the dorsal surface at each side. 

 The uterus is a long tube, having a characteristic convoluted course, 

 and opens anteriorly. The vagina starting from the ootype i& 

 straight (see 45). 



The life-history of Bothriocephalus is incompletely known, though 

 the development of the egg as far as the six-hooked embryo l has- 

 been carefully studied by Schauinsland (40). It is, on the whole, 

 similar to that of a Trematode, in the character of its segmentation, 

 at the end of which a "yolk envelope" of flat cells is formed, which 

 is left behind in the egg-shell (Fig. XL). Within this envelope 



1 The six-hooked embryo is also known as proscolex, onchosphere, and hexacanth. 

 erabryo. 



