CONTRIBUTIONS TO AMERICAN HELMINTHOLOGY. 63 
when viewed superficially, shows radial fibres and an irregular quad- 
rangular orifice ; but when the glass is pushed deeper, shows a doubly 
contoured ring 0.0135 mm. diameter, surrounded by circular fibres. 
(Fig. 21.) The ovary is somewhat bilobed, the ovarian eggs are 
polygonal from mutual pressure, and measure 0.009 mm. The fully 
formed egg differs much from Leuckart’s figure, and approaches those 
described by Olsson for various species of Octobothrium. Its oval 
body measures 0.195 mm. in length, while the whole egg is 1.04 mm. 
long. (Fig. 22.) 
The testis lies behind the ovary, and its vas deferens, surrounded 
by strong circular fibres, is continued forwards near the dorsal surface 
of the body. It probably opens by the same aperture as the oviduct ; 
at any rate, 1 have not been able to detect any trace of a second genital 
aperture. 
2.—POLYSTOMUM OBLONGUM, fn. sp. 
In September I had the opportunity of dissecting a single specimen 
of the Musk Turtle (Aromochelys [Sternothaerus] odoratus, Gray) : 
the only parasites obtained from it were four examples of an unde- 
scribed species of Polystomum found in the urinary bladder. No 
Helminths, as far as I am aware, have been hitherto obtained from 
this organ in Chelonia; the fact, however, that P. ocellatum is 
described from the cavity of the mouth in two Old World Turtles, 
suggested to me that I had perhaps in these a bladder stage of that 
worm, and that the two known species of Polystomum had in this 
way a precisely parallel history.“ A closer examination and com- 
parison with the characters of the two described species, showed that 
the worms presented peculiarities of specific value. I hope shortly 
to have the opportunity of examining the other turtles (Chrysemys 
picta, Chelydra serpentina) which are common in this neighbourhood, 
and have no doubt that Polystomes will be found in the oral cavity 
as well. An examination of the urinary bladder of Emys Europaea 
might not be without results in this respect. 
Descriretion (Figs. 9, 10. 11).—Body oblong, mouth on the ventral 
surface of the rounded anterior end. Pharynx bowl-shaped. Intes- 
tinal coeca without anastomoses or branches. Generative outlets in 
Front of the line of the lateral vagine. Cirrus-coronet of sixteen alter- 
nately small and large sabre-shaped pieces. Viviparous. Length up 
to 2.5 mm., breadth to 1.5 mm. Egg, greenish, 0.235 mm. x 0.195 
mm. Larva ocellate 0.5 mm. in length. 
21 For life-history of P. integerrimum, v. Zeller. Zeit. wiss. Zool. XXVII., p. 238 f. 
