CONTRIBUTIONS TO AMERICAN HELMINTHOLOGY. 69 
worms, as I find in two specimens the substance of the lamina pro- 
jecting beyond the level of the rest with the base of the hook lodged 
in it. 
Of the marginal hooks, most seem to have a trifurcate base, as 
represented in Fig. 14 (b) ; in others (a and c), there would seem to be 
a cbitinous ring at the point of attachment similar to those noticed in 
the large hooks of Dactylogyrus by Wagener and V. Linstow.* The 
hooks situated in the centre of the suckers (a) appear to be slightly 
different from the others, additional chitinous rings of smaller size 
being present. The hooks measure about 0.025 mm. in length. 
The mouth is situated in the middle of a somewhat funnel-shaped 
sucker upon the ventral surface of the head. From Dr. Osler’s 
sketch I make out that the pharynx is situated shortly behind the 
mouth, and that the intestinal coeca diverge immediately from this 
to arch into each other (as in some forms of Monostomum) in the 
posterior fourth of the body. 
The following is extracted from Dr. Osler’s notes: 
‘*The water-vascular system is well developed, beginning as a ramification 
of vessels about the anterior disc, and uniting to form two vessels, which run 
the whole length of the body, joining below, and opening somewhere between 
the posterior discs. Cilia are to be distinctly seen in the water-vascular sys- 
tem, especially at the junction of the tubes below. At the upper third of the 
body, on a level with the generative orifice, are seen on each side curious 
pulsating organs, which are undoubtedly connected with the water-vascular 
system, the pulsation occurring about once every minute and a half.” 
From the sketch accompanying this, these contractile bladders 
would seem to resemble in form, position and relative size, those 
represented in Epibdella Hippoglossi, by Van Beneden.” 
The lobes of the vitellogen occupy the sides of the body, but do 
not extend into the caudal Jamina, nor further forward than the 
generative aperture. 
This is situated immediately bebind the bifurcation of the intes- 
tine. I have only been able to determine its position from the 
cirrus-coronet in the mounted specimens. Dr. Osler, however, saw 
the female aperture quite close to this, leading into a “narrow, 
slightly-curved vagina.” This I have represented in Fig. 13; it is 
probably the unexpanded uterus. 
28V. Linstow, Trosch. Archiv., 1878. These seem also to be indicated in Zeller’s figure, loc, 
eit., Taf. XVII., Fig. 3. 
2 Mémoire sur les Vers Intestinavx, PL IL, Fig. 2 
