CONTEIBUTIONS TO AMERICAN HELMINTHOIOGT. ^B 



wlieri viewed superficially, shows radial fibres and an irregular quad- 

 rangular orifice ; but wben 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 aire 

 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, I have not been able to detect any trace of a second genital 

 aperture. 



2.— POLYSTOMUH OSLONGUM, W. 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. 



Desceiption (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 vaginae. 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 oceUate 0.5 mm. in length. 



21 For life-history of P. integerrimum, v. Zeller. Zeit. mss. Zool. XXVII., p. 238 f. 



