710 MR. F. F. LAIDLAW ON THE TOLYCLAD [Jime 19, 



situated at about a fifth of the total body-length from the anterioi" 

 margin. The pharyngeal opening is subcentral, and the pharynx 

 is fairly large and similar to that of Leptoflana in appearance 

 (see text-fig. Ill, p. 708). 



The gut-branches are numerous. 



The male and female genital ducts open together into a small 

 antrum at the extreme hind end of the body. 



The ejoidermis contains no rhabdites, but many of the cells 

 composing it resemble in appearance goblet-cells, and are no doubt 

 concerned in the production and excretion of mucus or pseudo- 

 rhabdites. The preservation of the epidermis is unfortunately 

 not good. 



The basement membrane is readily distinguishable in the 

 sections. Under it lie first a layer of longitudinal muscle-fibres, 

 within these are circular and diagonal fibres not differentiated into 

 separate strata, and lastly, on the ventral side only, an inner 

 longitudinal layer. 



As is the case in many other Polyclads, the main gut is clearly 

 marked ofi" from the branches by the fact that in its walls are 

 present large numbers of unicellular glands which are not present 

 elsewhere in the alimentary tract. 



The main features of the anatomy of this sjpecies are shown 

 diagxammatically in fig. 2 of Plate LII. 



Male apparattis. — The vasa deferentia unite below about the 

 hinder end of the large female accessory vesicle to form a single 

 rather convoluted duct, which runs backwards through a special 

 sheath or casing of tissue which appears to be prostatic in character. 

 In this part of its course the ductus ejaculatorius has a very thin 

 wall. As it approaches the antrum the wall becomes thicker, and 

 at the same time the tissue surrounding it takes on gradually a 

 definite muscular character. Finally the duct opens at the apex of 

 a small, conical, muscular penis which projects into the antrum 

 immediately below the termination of the vagina (PI. LII. fig. 2, S )• 



It will be most convenient to describe the female apparatus by 

 following its course in the opposite direction, that is to say 

 forwards. The vagina is a simple non-muscular tube which 

 leceives the secretion of the shell-glands near its termination and 

 runs forwards, lying at first above the sheath of the ductus 

 ejaculatorius. It passes beyond this for some distance, nearly as 

 far as the hinder level of the pharynx, there turning first upwards 

 and then backwards, it opens at once into a large accessory vesicle. 

 Just before this it receives the common opening of the two uteri. 

 Beyond the point where the shell-glands lie, the vagina is sur- 

 i-ounded along its whole course by unicellular glands which form as 

 it were a second outer laj^er of the wall of the duct. 



The accessory vesicle is large, non-muscular, with glandular 

 walls. It extends backwards nearly as far as the antrum, and is 

 distended with a granular secretion to such an extent that it 

 presses on and nearly occludes the lumen of the vagina when that 

 lies below it. 



