No. 404.] MWORTH-AMERICAN INVERTEBRATES. 649 
body very broad, often circular ; no eyes ; 
numerous testes: on gills or skin of 
marine fishes — Tristoma Cuv. (Fig. 9) 
f. Genital pores median or on right. Sucking disk 
with numerous radial rows of small hooks ; ante- 
rior suckers present (or in their place a pair of 
glandular depressions, Goto) ; numerous testes : 
n the skin of the skate 
Acanthocotyle Mont. (Fig. 10) 
£, Sucking disk pie to body by a long stalk ; genital 
res median . . Subfamily II. Encotyllabine 
Body elliptical ; anterior suckers large, stalked ; suck- 
ing disk without radial ridges and with two hooks : 
in mouth of marine fishes 
Encotyllabe Dies. (Fig. 11) 
d, Body elongate, cylindrical, and sometimes ringed ; sucking 
isk terminal, without radial ridges or hooks; pharynx 
cxtensible ; genital pores median ; no eyes : on parasitic 
crustaceans . . Subfamily III. Udonellinz 
Z,- Anterior e Deni, body ringed in youth; 
pharynx without hooks ; one testis : on Caligus and 
Anchorella. . . Udonella Johnst. (Fig. 12) 
é,. Anterior suckers abiedt but in their place a pair of 
projections : on Caligus. 
Body ringed ; anterior projections narrow, tentacle- 
like ; pharynx with two hooks 
Echinella v. Ben. et Hesse (Fig. 13) 
f. Body ringed in youth, swollen in middle ; anterior 
projections broad, membranous ; pharynx without 
hooks, but with a large number of minute rods 
: Pteronella v. Ben. et Hesse (Fig. 14) 
ĉc» Paired anterior suckers or projections absent ; sucking disk with 
or without radial ridges ; body flattened and usually broad 
Family III. Monocotylide 
d, Sucking disk very small, without radial ridges or hooks : on 
skin of selachians. 
e, Body elliptical, with truncated ends ; vagina paired ; 
testes usually numerous 
Pseudocotyle v. Ben. et Hesse (Fig. 15) 
€, Body elliptical, with attenuated ends ; vagina unpaired, 
opening on left of ventral surface ; one large testis. 
Microbothrium Ols. (Fig. 16) 
d, Sucking disk large, with radial ridges and (except in Lopho- 
hag two hooks; paired adhesive glands at anterior 
en 
r 
