660 THE ANIMAL KINGDOM. 



joint, one on each side, have been observed in the immature Schistocephalus 

 (Riehm 1 ). These ( foramina secundaria ' are probably more common than is 

 usually supposed. The excretory vessels of the scolex are continuous with 

 those of the proscolex. The latter appear to form a network, and open 

 posteriorly by a pulsatile vesicle. The contents of the excretory canals, 

 when extruded from the pulsatile vesicle or the foramina secundaria, ap- 

 pear to be immiscible with water. The granules suspended in the liquid 

 are sometimes calcareous in nature (see p. 227). 



All Cestoda are hermaphrodite. The male organs consist of a large 

 number of vesicular testes, of delicate efferent canals, of a vas deferens 

 which receives the latter and terminates in an evaginable portion or 'cirrus' 

 surrounded by a muscular envelope or ' cirrus sac.' The testes are more or 

 less globular, numerous, i. e. several hundreds in each joint of a large tape- 

 worm, but in the tapeworms of Birds especially only 2-3, scattered, and 

 usually confined to one aspect of the body hence termed dorsal (supra). 

 The vasa efferentia are extremely fine tubules, difficult to see unless 

 naturally injected with sperm. They unite inter se, but eventually open 

 by a larger or smaller number of canals into the vas deferens. This organ 

 may be single, or, as in Schistocephalus and Ligula^ double. It becomes as 

 sperm collects, disposed in loops or coils, and at the same time dilated, 

 especially towards its termination. In Bothriocephalus latus y Schisto- 

 cephalus ', and Ligula the dilatation or vesicula seminalis is surrounded 

 by an envelope of chiefly longitudinal muscle-fibres and forms a glo- 

 bular or ovoid body. The termination itself of the duct is single, usually 

 slightly coiled and is evaginable ; the evaginated portion constitutes the 

 cirrus or penis. The outer surface of the cirrus (the inner before evagina- 

 tion) is in some instances armed with spines, e. g. in Echeneibotkrium. 

 The female organs consist of two ovaries or germaria, of vitellaria, or the 

 homologous 'albumen gland,' a shell gland, uterus, vagina, and sperma- 

 theca. The germarium is rarely single, as in Caryophyllaeus and Ligtda. 

 It consists either of branching anastomosing tubes, as in the larger Taeniae, 

 Bothriocephalus^ Schistocephalus, and Ligula^ or of a small number of 

 vesicles attached to a slender duct, as in Taeniae, with narrow joints, 

 e. g. T. perfoliata ; or it may be vesicular, and either lobed, e. g. T. lineata, 

 or simple as in Caryophyllaeus. The vitellarium has much the same 

 structure as the germaria in most Taeniae, e. g. T. solium, T. mediocanellata, 

 and is a single gland placed near the posterior margin of the joints 2 . In 

 other Taeniae it is vesicular, e. g. T. echinococcus, and may be double, 

 e. g. T. lineata. It may have the form of a series of vesicles ranged along 

 either side of each joint, each series with its own duct (=vitello-duct), the 



1 Quoted by Kiesslmg, A. N. 48, (i\ 1882, note, p. 264. 



2 According to Moniez (' Les Cestodes,' p. 194 et seq.), this organ in the Taeniae named and 

 their allies, e. g. T. serrata, is an ovary or geimarium. 



