IGQ 



ZOOLOGY. 



in the young, and there are no suckers or hooks ; while 

 there is but a single set of male and female reproductiye 

 organs situated in the posterior end of the body, which can 



be detached from the ante- 

 rior part of the body, form- 

 ing a proglottis. In fa<;t, 

 this, foi-m is a connecting 

 link between the Trematoda 

 ■L- ■,■.-, TT ^ ^ T „ t ™ and Ce-stodes. CaryophyllcBus 



Fig. 111. — Head of T- c« o wry^ seen from , . _. 



above, iTltli circle of lirx>k3 : a— €. hooka; .//j2/^ajj7i'.<i Eudolphl lives m 

 all mnclienlaiged.— After Siebold. , . . .,-,.. 3 



the intestines of Cyprmoid 

 fishes ; the young in a worm, Tulifex rividorum. 



Tetraryhnchus is provided with four very long slender 

 extensile spiny cephalic processes or beaks. The young live 

 encysted in bony fishes, the adults occurring in the intestines 

 of sharks and rays. 



In Ligvla the body is ribbon -shaped, not jointed, with a 

 series of se.Yual organs, and there are no suckers, and some- 

 times no hooks. L. simplicissima Eud. lives in fishes and 

 amphibians, and attain maturity in the intestines of water- 

 birds, which feed on the former animals. This genus con- 

 nects the simpler tape-worms with Bofhriocejplialus and 

 TcRnia. 



Class I.— PLATTHELMIXTHES. 



More or leas jlatUned loorras, with the body umaVy ujtMgmented ; the 

 hiarl. in the Ceatodes often armed with Twoks ornuckers. Simpk or branched 

 {Turbeaaria) or forked {Trematoda) dige^ti^ tract, but no general body- 

 canily. -(The digesthe camty is entirely warUing in the Ce^'odes.) Serrois 

 system represented by a double cephalic ganglion, mth two or more nervoai 

 cords. A system of tessds corresponding to tlie irater-rasculai- system of 

 Eclnnodfrms, but supposed to be mainly excretory in function. Morue- 

 cious, rri rely bi-sexual. Ornries differentiated into a germigene and vitel- 

 logene; often parthenogenetic. accompanied by strobilation in the tape- 

 irot-ms. When nlternatitui of generations occurs by budding, the sexual n ni- 

 rnuU are united leith their nurse or a sexu-dform into a polymorpa ic colony. 

 Order 1. TurbeUaria. — Flattened ovate worms, with a nervous gan- 

 glion in the head ; usually eye-sx)ecks : body externally cili- 

 ated, with a much-branched digestive canal. Nettling 

 organs often present. Bisexual, rarely unisexual; strobi- 



