38 Art. 3.— T. Kabin-aki : 



alwaj^s distinctly marked b}^ numerous eosinophil glands which 

 open into its lumen. 



So far as I have observed, the vagina is not very conspicuous 

 in Ect limuU, and the uterus opens almost directly into the 

 postero-superior part of the vestibulum by a very short, narrow 

 stalk, which may perhaps represent the vagina. 



Genital Atrium. — Before proceeding further, I shall in the 

 first place proceed to state as to the genital aperture. As alread}^ 

 noted down, it in Pr. lactea is situated at a distance behind the 

 mouth equal to about one-fifth that between the latter and the 

 posterior body-end, in St. trigonocefliala a little in front (»f the 

 middle betwee.n them and in Ect. limuli in ft ont of the middle of 

 the posterior third of the body. The opening is lined b_y a ciliat- 

 ed epithelium continuous with that of the body. In St. trigouoce- 

 phala and Ect. limuli some eosinophil glands open out on the 

 ventral body-surface around the genital opening. 



The aperture leads into an atrial cavity, wliicli may l)e dis- 

 tinguished into two portions, viz., a penis-sheath and a vesti- 

 bulum, the general structure of which it wnll be necessary to 

 describe here, beginning with the penis-sheath. 



Penis Sheath. — The lining epithelium of this is continuous 

 with that of the penis ; in Ect. limuli it shows no nuclei, which 

 are apparently displaced just beneath the muscular layer. Usually 

 the epithelium rests upon a delicate basement membrane, out- 

 Avards to Avhich come two muscular layers of internal circular and 

 external longitudinal fibres. In Si- trigonocejyhala the cavit}- soon 

 opens to the exterior by way of the minute aperture; Avhile in Pr. 

 la<;tea and Ect. limuli it communicates with the vestibulum. 



Vestibulum. — In Pr. lactea this is a moderately distended 

 cavity situated just inferior to the penis-sheath, and apparently 

 separated from it by a constriction. The wall presents quite or 

 almost the same appearance with tliat of the penis-sheath. St. 

 trigonocephala shows an aspect quite like Pr. ohlini, and no special 

 vestibulai" part is present in it. 



The vestibulum presents in Ect. limuli the most peculiar 

 aspects. It is a deep and wide cavity, which ascends vertically up 



