812 THE AMERICAN NATURALIST. [Vor. XXXIV. 
is about two-thirds the length of the animal from the anterior 
end. The surface of the body is thickly set with minute scales 
or spines, which diminish in size toward the posterior extremity. 
The sexual orifice is near the left side, ventral, rather nearer 
to the oral than to the ventral sucker. The excretory pore is 
dorsal, nearly terminal, median, 
j surrounded by a small cluster of 
gland cells. | 
The pharynx is small and 
placed immediately behind the 
oral sucker, and is followed at 
once by the bifurcation of the 
intestine. The limbs of the in- 
testine are short and sac-like, 
extending backward, not farther 
Fic. r. — Outline deny. d 7 D. arcanum, 
showing positions of 
from ventral si 
ral side. Uterus (except termi- 
nal portion) not repres C 
than the middle of the body. 
The walls are thin and feebly 
developed. 
The ovary is irregular in form 
or lobulated, and is situated just 
rynx; As, penis 
a v, vitellary glands; vs, 
behind the forking of the in- 
testine, a little to the right of 
the median line. Vitellary glands lying nearer the ventral 
surface are irregularly distributed through a zone extending 
from about opposite the pharynx back nearly to the ventral 
sucker. They appear as small cell-clusters or masses having 
a loosely dendritic arrangement. 
The region of the union of the oviduct with the ducts from 
the vitellary glands and of the giving off of Laurer’s canal is in 
the central portion of the body, just back of the ovary and nearer 
the dorsal surface, but the exact arrangement of these tubules 
I have not made out. The shell gland is readily seen in sec- 
tions but not usually evident in entire preparations. Laurer's 
canal opens on the dorsal surface posterior to the ovary, nearly 
overthe ventral sucker. The oviduct or uterus fills the greater 
portion of the space remaining between and around the other 
internal organs, but its folds appear to lack any definiteness of 
arrangement, 
$c; 7, 
ventral suck 
