14 Laidlaw, Classification of the Poly clad Turbellaria. 



In dealing with Enstylochus, Verrill for the same reason has 

 not, I believe, determined the real course of the vagina, which 

 probably differs from that of such a form as Stylochoplana agilis 

 chiefly in having the uterine opening placed at a different, that is 

 a posterior, level. 



In my account of Parapla?tocera langi I find I was in error 

 in describing the shell-glands as lying close above the female 

 aperture. A careful re-examination of my sections has shown 

 that there are no shell-glands in that position in any of the three 

 species of the genus at present known, and that the tissue which 

 I supposed to be shell-glands, in the case of P. langi, though 

 in a bad state of preservation, is probably muscular. The 

 receptaculum seminis, as described in my account of that species, 

 is lined with secretory epithelium. This may be held to account 

 for the unique position of the shell-glands in Disparoplana^ 

 namely behind the uterine opening. 



Note B. — Verrill's Iwo genera Eustylochus and Planoceropsis 

 are to be referred to this division ('88). Eustylffchus appears 

 most closely allied to Idiopla^ia from the structure of its genital 

 organs, the exact affinities of Planoceropsis are more doubtful. 

 It will be noticed that both these genera are provided with 

 nuchal tentacles and marginal eye-spots. 



A recently described new genus Shelfordia v. Stummer- 

 Traunfels {:02a) with one species, from Borneo, interesting as being 

 the only known fresh-water Polyclad, would appear also to be 

 related here. It has no tentacles but possesses marginal eyes. 

 The long narrow prostate is described as ending blindly, and is 

 said to be wound round the conical vesicula seminalis. 



Note C- — The American species referred to Trigonoporushy 

 Verrill ('88) can hardly remain in the genus if it is to be clearly 

 defined. I am inclined to believe from Verrill's figure of the genital 

 apparatus of his species {T. folium) that they may ultimately 

 be found to have some affinity with Planocera. Certainly his 

 figures ('88, pi. XLiv., fgs. 4-7) show indications of an outer 



