66 



THE TREMATODA 



the name F. hepatica ovata. But Retzius (1776) invented the name 

 Distoma for the Trematodes, of which several were then known, retaining 

 Fasciola for something quite different (viz. Gordius) ; 0. F. Miiller 

 (1776) also separated Linne's Fasciola into two, retaining the name for 

 a Trematode and giving Planaria to the Turbellarian, and for some 



FIG. XI. A Group of Distomidae. 



1. Distomum variegatum, Rud. (after Looss), from the lung of Rana esculenta, to show the 

 general shape and disposition of the suckers. Its anatomy agrees closely with the generalised 

 "type "(see Fig. IX.). 



2. D. confusum, Looss, from the intestine of frog and toad. The genital pore has shifted 

 in this and some other species to the left margin of the animal. In this case the other organs 

 have undergone peculiar shiftings from the normal. The testes and vitellaria are anterior. 

 (After Looss.) 



3. D. acanthocephalum, Stoss. (after Stossich), from the rectum of Belone ams. t, hooklets. 



4. D. miescheri, Zsch. (after Zschokke), from the oesophagus of Trutta solar ; side view to 

 illustrate the fact that the male (<$) and female pores (9) may be separate. 



5. Koellikeria filieolle, Rud. (D. okenii, Kol.), from cysts in the branchial chamber of Brama 

 raji (partly after Kolliker). 



6. D. nodulosum, Zed. (after Looss), from the intestine of Acerina cernua, to show tentacles. 



7. Rhopalophorus horridus, Dies., from the duodenum of Didelphys myosurus ; ventral view 

 (after Diesing). r, armed tentacles. 



8. D. verrumsum, Poir., from stomach of Thynnus (after Poirier). 



a, mouth and oral sucker ; 6, genital pore ; c, ventral sucker ; d, intestine ; /, vitellaria ; 

 e, testis ; g, cirrus ; h, vaginal region of uterus ; i, cirrus sac ; j, seminal vesicle ; fc, uterus ; 

 I, germarium ; m, spermatheca ; s, enlarged sac of 9 Koellikeria ; o, excretory pore. 



time Fasciola hepatica was the name of the liver-fluke. Zeder and 

 Rudolphi, however, returned to Retzius's name Distoma, which Nitzsch 

 (1816) altered to Distomum; and since that time, with a few dissentients, 

 this modification of Retzius's name has been employed. 



The anatomy of the liver-fluke may be found in nearly every text- 

 book, and has been the subject of much work by Leuckart in his well- 



