658 THE AMERICAN NATURALIST. |. [Vor. XXXIV. 
KEY TO THE SPECIES OF NoRTH-AMERICAN HETEROCOTYLEA. 
GENUS TEMNOCEPHALA. 
Body ovoid ; tentacles five in number, long and slender ; pharynx very 
large, intestine short but broad, with a pair of lateral anterior projections ; 
.5-1 mm. long, .2 mm. wide: on carapace of Cambarus Digueti (Mexico) 
T. mexicana Vayssieére (Fig. 1) 
GENUS EPIBDELLA. 
Body flat, smooth, ovate, slightly constricted behind the anterior suckers ; 
anterior suckers crossed by twenty-two ribs ; posterior sucker attached by 
pedicel at posterior margin of body, elliptical, with four hooks ; 12.5 mm. 
long, 8.35 mm. wide: on skin of Dasyatis centura (Woods Holl) 
4 E. bumpusii Linton (Fig. 5) 
GENUS TRISTOMA. 
a,. Diameter of sucking disk less than a third the length of the body. 
à,. Body ovate ; sucking disk small, less than a quarter the length of 
body and but little larger than the anterior suckers ; 10 mm. long, 
7 mm. wide: on gills of Tetrapturus albidus 
T. cornutum Verrill 
b, Body heart-shaped ; color white, with small oval spots on the 
dorsal surface ; anterior end between the anterior suckers fringed ; 
22.5 mm. long, 18 mm. wide : on the body of Diodon (California) 
T. maculatum Rud. 
č% Body nearly circular, ventral periphery with short, radial rows of 
papille, and dorsal surface with several series of pointed black 
papille ; sucking disk with crenulate border, and not reaching the 
posterior end of body ; 15 mm. long, 12 mm. wide : on gills of 
sword fish (Woods Holl, Linton) . . ‘occineum Cuv. (Fig. 9) 
. Diameter of sucking disk equals one-third or half the length of body. 
; Body circular, ventral surface covered with papilla ; sucking disk 
large, its diameter equaling half the length of the body, and with 
a large central area; 15 mm. long, 14 mm. wide: on gills a 
Tetrapturus albidus (Woods Holl, Linton) . T. læve Verrill 
d» Body almost circular, slightly attenuate forward ; sucking disk large, 
its diameter equaling one-third the length of body, and with a 
plicate membranous border ; 18 mm. long, 19 mm. wide : on Mola 
mola (Woods Holl, Linton) . . . . . . T. mole Blanch. 
A 
tS 
GENUS NITZSCHIA. 
& 
m 
. Body lanceolate, reddish, contracted posteriorly ; sucking disk globose ; 
anterior suckers large, linear, oblique ; mouth triangular ; 16 mm. 
