174 



PLATHELMINTHES 



.,.-2 



Key to the genera of Tristomidae here described: 



Oi Sucking disc not set off from body and with 7 radial ridges. . .1. TRISTOMA 

 a 2 Sucking disc set off from body and without radial ridges. 

 bj. Body elongate; sucking disc terminal with many minute hooks. 



2. NITZSCHIA 



6, Body elliptical ; sucking disc ventral with large hooks 3. EPIBDELLA 



1. TRISTOMA Cu- 

 vier. Body very flat, 

 circular, or oval, with 

 a pair of anterior suck- 

 ers and a large ventral 

 sucking disc in which 

 are 7 radial ridges and 

 small hooks ; intestine 

 with side branches; 

 genital pores near the 

 margin of the body; 

 many testes present : 

 about 10 species. 



T. coccineum Cuv. 

 (Fig. 279). Body about 



15 



16 



Fig. 279 Tristoma coccineum (from Bronn), 

 References as in Fig. 278. 



mm. long and 

 mm. wide and red in 

 color: on the gills of 

 the swordfish. 



2. NITZSCHIA von Baer. Body elongate, with sucking disc terminal 

 and without radii; 2 large suckers at forward end; numerous testes: 1 

 species, in salt and fresh water. 



N. sturionis (Abildgaard) (Fig. 280). Body red- 

 dish, 16 mm. long, 5 mm. wide; sucking disc globose: on 

 gills of the sturgeon. 



3. EPIBDELLA Blainville. Body elliptical and flat; 

 sucking disc ventral without ridges, but often with 

 papillae; 4 small eyes; 2 testes: several species. 



E. bumpusi Linton (Fig. 281). Length 12 mm.; 

 width 8 mm. : on skin of Dasyatis centrura; Woods Hole. 



FAMILY 2. MONOCOTYLIDAE. 



Flat and circular or elliptical worms without paired 

 anterior suckers and with a single posterior sucking plate, 

 which is sometimes very small : on the skin, gills, or in the 

 cloaca of marine fishes; 7 genera. 



MONOCOTYLE Taschenberg. Sucking disc with 8 radial ridges; 

 1 to 3 testes: on the skin or gills of skates. 



Fig. 280 



Nitzschia 



sturionis 



(Monti celli). 



References 



as in Fig. 278. 



