THE FREE-LIVING FLATWORMS (TURBELLARIA) 



353 



75 (76) With a single sexual pore Family PoLYCYSTmmAE. 



Two ovaries, two yolk glands with linger-like lobes, and two compact testes. Bursa copu- 

 latrix small and without a separate external opening. 



Single genus thus far found in America Polycystis. 



Only one species known in America. . Polycystis roosevelti von Graff 191 1 . 



Length 2 mm. Anterior end of body transparent, the rest of the body faintly 

 reddish. A subcutaneous brown pigment between the longitudinal muscle fibers 

 gives a more or less striated appearance. The extremely flexible proboscis lies 

 within its sheath just in fr.ont of the brain at the anterior end. The mouth 

 and pharynx lie in the beginning of the second third of the body and the genital 

 pore Ues between the second and last third of the body. Posterior end very 

 bluntly rounded, anterior end somewhat narrower. Closely resembles the 

 European species P. gaetli Bresslau except in the structure of the chitinous 

 portion of male copulatory organ. 

 Fig. 626. Polycystis roosevelti. Chitinous cirrus tube with buib (6), ductus semioali 

 (rfs), and the ducts leading from the granular glands [kd). X 400. (After von Graff.) 



With two sexual pores, the male posterior to the female. 



Family Gyeatricidae. 

 One or two ovaries, with yolk glands and one compact testes which lies on the left side. 



Only one genus known Gyratrix. 



Single species known in America. 



Gyratrix hermaphroditus Ehrenberg 1831. 

 Length 2 mm. White in reflected light. Eyes black. Without rhabdoids or pigment. 

 Capable of contracting into a ball, or extending to almost double its length as long as it remains 

 actively swimming. Stiletto-sheath of male copulatory organ a short wide tube. The 

 very large bursa copulatrix has a separate dorsal opening to the exterior. Egg capsule oval. 

 From peat bog, Rochester, Monroe Co., N. Y. 



One subspecies Gyratrix hennaphrodilus hermaphroditus Ehrenberg. Stiletto-sheath with a 

 hook on the end. The egg capsule is gradually reduced to its stalk and is much elongated. 

 Rhabdoids occur in the terminal cone of the proboscis, 



-po 



76 (7S) 



Fig. 627. Gyratrix^ hermaphroditus . {A) Ventral view of compressed specimen, do, dorsal opening 

 of; be, bursa copulatrix; ch, chitinous tube; chst, stalk of chitinous tube; chg, chitinous stiluto leading 

 from vesicula granulorum; ec, egg capsule in uterus; ov, ovary; gd, granular secretory glands; ko, external 

 opening of kidney; ph, pharynx; rim, attachment of the long proboscis retractor muscles; ec, end coue 

 of proboscis; rm, muscular portion of proboscis; po, external opening of proboscis sheath; te, testes; 

 tfti, vas deferens; ug, vesicula granulorum; hi, yolk glands; w, vesicula seminalis; cf, male and 9 . female 

 genital pores. X 30. (After von Graff.) (B) Stiletto-sheath with straight tube, o, opening of stiletto 

 sheath; ch, chitinous stiletto of cirrus. Much enlarged. (After Hallez.) (C) Gyratrix hermaphroditus 

 kermai>hroditus. Stiletto -sheath with curved point. Much enlarged. (After von Graff.) 



