I9I4-J F- H, Stewart : Indian Heluiinthology, No. II. 203 



(5) Polystomum hassalli. Goto 1898 (Lit. No. 10). From 

 the urinary bladder of Kinostenion pennsylvanicum, in Bowie, 

 Prince George county, Md. 



" Total length of the body i"5 mm. Body proper ovate. 

 Adhesive disk hexagonal, the hemispherical suckers occupying the 

 angles of the hexagon and each with a minute hook in the centre, 

 with three pairs of hooks between the most anterior pair of 

 suckers and two pairs between the most posterior; these hooks 

 and those in the suckers being all of the same form and measuring 

 0*033 mm. in length. The larger hooks between the most 

 posterior suckers bifurcated towards the base, without any lateral 

 process, measuring 0'i25 mm, in length." 



Polystomum hassalli is therefore four times as long as P. 

 kachugae, possesses five pairs of small cot3dophore hooks in place 

 of one, and a booklet in each sucker which does not exist in P . 

 kachugae. 



Goto describes the alimentary system of his species as fol- 

 lows :— " Anterior sucker large, oesophagus wanting, intestine bifur- 

 cated, tubular, without lateral branches, the two legs ending 

 independently at the front end of the adhesive disk." The 

 mouth of P. kachugae is not surrounded by a sucker : it is possible 

 that Goto refers to a structure of the same nature as the first 

 pharynx of P. kachugae. 



"Common genital pore" (in P. hassalli) "lying midway 

 between the front end of the body and the front end of the 

 adhesive disk. I counted fifteen penis spines which are straight 

 and bear a wing-like process at the middle and are 0*028 mm. 

 long, but as their number in other species is always even, I think 

 that there are sixteen in the present species." The distance of 

 the atrial pore from the anterior extremity of the body in P. 

 kachugae is about one-fifth of the distance of the anterior end of 

 the cotylophore from the same point. 



The ovary of P. hassalli lies as in P. kachugae sometimes in 

 the right half of the body, sometimes in the left half. The vaginal 

 openings are lateral, without papillae, midway between the front 

 and hind extremities of the body proper ; the two vaginal canals 

 are directed almost straight across the body and meet in the 

 median line. In P. kachugae on the contrary the vaginal openings 

 are situated at the junction of the anterior and middle thirds of 

 the body proper. The genito-intestinal canals of P. hassalli lie 

 slightly behind the vaginae, in P. kachugae slightly in front of 

 them. 



(6) Polystomum sp. (P. ohlongum, Leidy, 1888, not the true 

 P. ohlongum, Wright, 1884) (L,it. Nos. 13 and 10). From the uri- 

 nary bladder of Pseudemys rugosa. 



This species is partially described from an imperfect specimen 

 by Goto, but it is not named on account of the inadequac}^ of 

 the description. 



It possesses sixteen equal penis spines measuring o'66 mm. 

 in length (in contrast to the unequal spines in Wright's species) 



