256 



PLATYHELMINTHES. 



specialized form, in which the sexual persons produced by division 

 have lost their distinctness and do not separate from the colony. 

 In other words, Ligula bears the same relation to a sharply seg- 

 mented tape-worm that a hydroid colony with medusoids bears to 

 a colony which buds off free-swimming medusae. Bothriocephalus, 

 in which the segments separate off in groups (Fig. 214), may be 

 regarded as a stage on the road to the condition found in Ligula. 



Fam. 1. Cestodariidae. The body is unsegmented and the generative organs 

 are not repeated. Archigetes Lkt. A. Sieboldii Lkt. (Fig. 211), in the body- 

 cavity of the generative segments of Tubifex rivulorum, about 3 mm. long, with 

 caudal appendage (? Onchosphere) which carries three pairs of small hooks at its 

 free end. The anterior end of the body has two weak suckers. 

 Life-history unknown. The only Cestode which attains sexual 

 maturity outside the Vertebrata. It is to be regarded as a 

 Cestode retaining the Onchosphere, and still fixed by the 

 embryonic hooks. Caryophyllaeus Mill!., elongated, no ex- 

 ternal distinction between head and body, without suckers ; 

 excretory opening at hind end ; genital pore on ventral surface 

 of hind end, receives the vas deferens, uterus, and vagina. 

 C. mutabilis Rud. (Fig. 212), intestine of Cyprinoids, asexual 

 form probably in Tubifex rivulorum. Amphilina Wagoner, 

 body-cavity of sturgeons, A. foliacca Rud. (Fig. 213). Body 

 flattened, Trematode-like, 60 mm. long, pointed at one end 

 which carries a sucker near by the opening of the uterus 

 (TJt.ni) ; the vagina (Vg) and vas deferens (C) open at the 

 other end; body -cavity of sturgeon; produces a partially 

 ciliated hooked embryo, life -history unknown. Gyrocotyle 

 Dies. (Amphiptyches Wagener), alimentary canal of Holo- 

 cephali, a sucker at the anterior end, edge of body folded. 

 Uterus, vagina, vas deferens open separately ; G. urna W. , 

 alimentary canal of Chimaera. The Onchosphere probably 

 passes into bivalves. Wageneria Monticelli, in Scymnus 

 nicaeensis. 



Fam. 2. Bothriocephalidae. With only two suckers, which 

 are weak and flat. Generative organs usually open on the flat 

 surface of the proglottis. Proglottides are often detached in groups. Hydatid 

 stage represented by an encysted scolex (Fig. 215), which is usually found 

 in fishes. Bothridinm Blainv. (Solenophorus Creplin) intestine of pythons and 

 boas ; Diplocotyle Krabbe, intestine of fishes ; Diphyllobothrium Cobbold, 

 intestine of dolphin ; Ptychdbothrium Lonnberg ; Duthiersia Perrier, from 

 Varanus. 



Bothriocephalus Brems. Segmented body. Head with two pits, without 

 hooks. The genital openings are on the middle of the ventral surface. The 

 young stage usually in fishes. B. latus Brems. (Fig. 214), the largest of the 

 tape-worms parasitic in man, twenty-four to thirty feet in length, principally 

 found in Russia, Poland, Switzerland, and South France. The sexually mature 

 segments are broader than they are long (about 10-12 mm. broad and 3-5 mm. 

 long). They do not become detached singly, but in groups (Fig. 214). The 

 segments of the hindermost portion of the body are, however, narrower and 



Fio.211. Archi- 

 getes Sieboldii 

 Lkt. (after 

 Leuckart). 



