POLYCLAD TURBELLARIA. 133 



pseudorhabdites. The basement membrane is very thick, especially on the dorsal 

 side ; on the other hand, the muscles of the body-wall are but feebly developed. 



The pha'rynx is large and much folded. The gut-branches are numerous ; there is 

 no anastomosis. 



Genital Apparatus. Reference to the Plate, fig. 8, will render the account given 

 below more readily intelligible. 



Terminal Male Organs. The two wide vasa deferentia (i\<l.) unite to enter a 

 median duct running to the penis. The proximal end of this duct is slightly swollen 

 and has rather thick muscular walls ; this part may be regarded as a vesicula 

 seminalis (v.s.). Beyond it the duct (d.e., ductus ejaculatorius) runs into the penis (_/'.), 

 a large fleshy organ which projects backwards and downwards into the spacious 

 antrum masculinum (a.m.). At its free end the penis is studded with a ring of^ 

 curious large glands evidently of a prostatic character (pr.gl.), which lie around the 

 rather wide ojtening of the lumen of the penis. These glands appear to be precisely 

 similar in character to those found in Discocelis tigrina. As in that species, other 

 glands of the same character are found on the walls of the antrum, but in the present 

 instance they lie at the free ends of certain curious muscular prominences which 

 project from the walls of the antrum. They are distributed as follows : In front of 

 the penis there is a crescentic muscular ridge which carries a number (about 15) of 

 these glands. In the diagram it is shown in section at rn.pr.', the glands are marked 

 pr. gl., and they project at their distal ends to some extent from the surface of 

 the ridge. 



Behind the penis there lies on either side of the middle line a pair of prominences 

 shaped rather like the penis, but folded in towards each other. Like the penis, they 

 each carry glands, 3 or 4 apiece at their free ends. They are indicated on the 

 diagram at m.pr." (see too, Plate, fig. 4). The floor of the antrum is formed of 

 a very thin fold of the integument, which extends backward as far as the level of the 

 paired prominences spoken of above. The antrum is lined throughout with a thin 

 layer of flattened epithelium which bears very short cilia. 



The glands have a length of about 0*1 millim. They are pear-shaped, their narrower 

 end is directed outwards and ends in a conical point which passes through the 

 epithelium lining the antral walls (Plate, fig. 5, a.gl.). The gland is in every case 

 filled with a fine darkly staining network, in the interstices of which in some of the 

 glands lies a quantity of finely granular secretion. The nuclei lie about the walls of 

 the gland, none occur in the reticulum. The walls are without muscle fibres. 



Female Terminal Ducts. These bear a very strong resemblance to those of 

 Discocelis tigrina. The female aperture opens into the terminal part of the vagina 

 (ya.), which is at first rather wide and runs in a dorsal direction. It then turns 

 backwards, its lumen narrows, and its muscular walls become thicker. After 

 receiving the common opening of the uteri (ut.) it is prolonged back for some 

 distance. This hinder part may be termed the accessory part of the vagina (ace. in 



