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 (6) ; in others {a and c), there would seem to be 

 a chitinous 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 

 diflferent 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. Osier's 

 sketch I make out that the pharynx is situated shortly behind the 

 mouth, and that the intestinal coeca diverge immediately from this 

 to ai'ch into each other (as in some forms of Monostomum) in the 

 posterior fourth of the body. 



The following is extracted from Dr. Osier's notes: 



"Tke 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-vascnlar 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 halt. " 



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 lamina, nor further forward than the 

 generative aperture. 



This is situated immediately behind the bifurcation of the intes- 

 tine. I have only been able to determine its position from the 

 cirrus-coronet in the mounted specimens. Dr. Osier, 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. 



28 V. Linstow, Trosch. ArcMv., 1878. These seem also to be iadicated in ZeUer's figure, loc, 

 ,«it., Taf. XVII., Pig. 3. 



29 Heanoire sur lea Vers Intestinaiw, PL II,, Fi^. 2. 



