240 



PLATYHELMIXTHES. 



tail. Rhopalophorus Dies.; Koellik.eria Cobb., dioecious, living in pairs con- 

 tained in cysts in the mucous membrane of the mouth and branchial cavity 

 of fishes ; the one individual is cylindrical and narrow, and produces sperma- 

 tozoa ; the other is swollen in the middle and posterior region of the body, 

 and is rilled with eggs. The dissimilar condition of the two individuals is 

 probably due to the fact that copulation only leads to the fertilization of one 

 of them, which alone is able to perform the female sexual functions. K. filicolle 

 Rud. (D. Okenii Roll.) in Brama Raji. Bilharzia* Cobb. (Fig. 192), dioecious ; 

 body elongated, nematode-like ; the female is slender and cylindrical ; the male 

 has powerful suckers and the margins of its body are bent round so as to form a 

 groove the canalis gynaecophorus for the reception of the female ; they live in 

 pairs in the blood-vessels of mammals. B. haematobia Cobb., portal veins and 

 veins of bladder of man in most parts of Africa. The 

 embryos, which are ciliated, escape by the urethra. 

 By the deposition of masses of eggs in the vessels of 

 the mucous membrane of the ureter, bladder, and 

 great intestine, inflammation is set up which may 

 cause haematuria and stone. B. crassa Sons., in Bos 

 taurus domesticus ; B. magnet, Cobb., in Cercopithecus 

 fuliginosus. 



Fam. 4. Gasterostomatidae. With the anterior 

 sucker only ; mouth on the ventral surface, not in 

 the sucker ; eggs with operculum, without filament. 

 Genital opening terminal, at hind end. The Cercaria 

 is known as Bucephalus, and has a bifid tail. In 

 alimentary canal of fishes. Gasterostomum v. Sieb. 



Fam. 5. Didymozoonidae. With the anterior sucker 

 only ; mouth in the sucker ; gut present or absent. 

 Hermaphrodite, but live in pairs in cysts. Eggs with 

 operculum without filament. Genital pore in front of 

 the oral sucker, terminal. On the integument, or in 

 the mouth and branchial cavity of marine fishes. 

 Didymozoon Tschbg. ; Nematobothrium v. Ben. 



Fam. 6. Monostomatidae. With only one anterior 

 sucker. Mouth in the sucker. Genital pore usually 

 in front, median, ventral. Eggs often with two fila- 

 ments. Laurer's canal usually absent. In alimentary 

 canal of most vertebrate classes. Monostomum, Zed.; M. lentis v. Nord. , the 

 young form without generative organs is found in the lens of the human eye ; 

 M. bipartitum Wedl., living in pairs enclosed in a common cyst, the one 

 individual surrounded by the posterior lobe of the other, branchiae of Tunny- 

 fish ; Notocotyle Dies. ; Ogmogaster Jaegerskiold ; Opisthotrema Leuck. 



THE DICYEMIDAE AND ORTHONECTIDAE.t 



The systematic position of these forms is obscure : it will, hoAvever, be con- 

 venient to place them provisionally near the Trematoda. They all consist of an 



* G. Fritsch, " Zur Anat. d. Bilharzia haematobia Cobb.," Arch. f. Mic. 

 AnaL, 31, 1888. 



t C. 0. Whitman, "A contribution to the embryology, life^history, and 

 classification of the Dicyemids," Naples Mittheilungen, Bd. 4. 1882. Julin C., 

 "Contribution a 1'histoire cles Mesozoaires," Arch, de Biologic, Bd. 3, 1882. 



FIG. 192. Bilharzia haema- 

 tobia. Male and female, 

 the latter being in the 

 catialis gynaecophorus of 

 the former. S sucker. 



