| ee PROCEEDINGS OF THE NATIONAL MUSEUM. 97 
_ The body, behind the ventral sucker, appears to be subcylindrical, 
_ but is characterized by a profound groove on the ventral side, the edges 
of which consist of ventro-marginal flaps, which separate anteriorly on 
either side of the ventral sucker, in front of which they disappear. 
Neck flat on ventral side; mouth subterminal, large; ventral sucker 
near anterior end, short-pedicilled, circular, with thickish, prominent 
or reflected border; reproductive aperture in front of ventral sucker. 
Surface of body, from and including ventral sucker, smooth ; remainder 
of body on back and sides more or less tuberculous; tubercules speci- 
ally abundant on dorsal region just back of ventral sucker. The ven- 
tral surface is crossed by transverse rugie, which, together with the 
disk of the ventral sucker, are minutely tuberculated. It is probable 
; that the ventral surface in life does not appear to be grooved, but rather 
flat. ; 
The fragmental specimen had the following dimensions in millimeters: 
Length, 5.5; diameter of neck, 0.4; diameter behind ventral sucker, 0.7; 
ventral sucker, 1.4 back of head; diameter of mouth, 0.4; diameter of 
vetral sucker, 0.6. A central tubular organ containing a coiled duct, 
presumably the uterus, extended back from the posterior end of the 
fragment 1.4 millimeters. This tube was 0.27 millimeter in diameter 
and the contained duct 0.06 millimeter in diameter. The thin walls of 
this tube were minutely roughened. The tubercles on the surface of 
the body are short and blunt and measure 0.025 millimeter in length. 
In most cases their breadth equals their length. 
The imperfect specimen was stained and cut into longitudinal sec- 
tions. The specimen is immature and the sections do not show much 
that can be made out definitely. The alimentary canal is bifurcate, but 
otherwise there is little resemblance to any Distomum or even Trematode 
with which I am familiar. The reproductive aperture lies in a groove 
on the ventral side of the neck in front of the ventral sucker, and a 
little forward of the bifurcation of the intestine. A series of oval masses, 
which lie along the dorsal region are probably the vitellaria. The 
exact nature of the cylindrical tube with its contained, convoluted duct, 
which protrudes from the center of the posterior end of the fragment 
‘was not determined. 
The neck of the entire specimen was much flatter than the body 
proper, which was subcylindrical, i. ¢., compressed so that its dorso- 
‘ventral diameter was less than its lateral diameter. The diameter, lat- 
eral, of the head was 0.3 millimeter; the breadth of the neck midway 
between the mouth and ventral sucker was 0.7 millimeter; greatest 
diameter of the body, 0.3 millimeter ; diameter of the posterior end, 0.3 
millimeter ; length of the spiral, 2.3 millimeters; entire length of spec- 
imen, 8 millimeters! Two sinuous dark-colored lines traverse the back 
along the posterior two-thirds of the body. These are probably the 
genitalia showing through the dermis. 
Hapirat: Larus californicus, intestines, Yellowstone Lake, August, 
1890. 
z Proc. N. M. 92 7 
nl > 
