3(3 Alt. 3.— T. Kalmiaki : 



sunken epitlielium for a short distance before the opening (PI. I,, 

 fig. 5). Numerous glands make their passage to the lumen of the- 

 vagina just inferior to the point where the latter receives the 

 oviducts. In Ed. limuli the hindmost part of the latter receives 

 the openings of the glands before opening into the vestibulum. 



The lining epithelium of the oviduct is generally composed of 

 normal ciliated cells with the exception of the proximal part of 

 the same in St. trigonocephala., as described just above. Im- 

 mediately outwards to the epithelium there exists a feeble mus- 

 cular laj^'er of circular and longitudinal fibres. 



Receptaculum Seminis {Uterus). In one leceptaculum-bearing 

 marine Triclads, except Uteriporiis, the receptaculum alwa^^s lies 

 behind the male organ. In Fr. lactea it is a spherical sac-like 

 organ lying dorsally in the parenchyma, and it is lined with an 

 epithelium of large cuboidal cells, which usualh'^ possess an avoid 

 nucleus closs to the base-. The appearance of the cells varies 

 much with the state of their secretory activity; at the basal portion 

 the protoplasm is usually homogeneous and deeply stainable, 

 while at the distal portion it is vacuolated in consequence of the 

 discharge of the secretory product. The cells rest upon a delicate 

 basement membrane, beneath which are fine circular and longitu- 

 dinal muscles. In iSt. trigonocephala the receptaculum is a large 

 sac-like organ which is Hned with a relatively thin epithelium, 

 showing either uniformly homogeneous or very finely granular 

 appearance. The nuclei are present near the base. In im- 

 mediate contact with the epithehum is a fine basement membrane 

 outwards to which comes a muscular layer, quite similar to that 

 of the preceding. In Ect. limuli this organ is moderately large, 

 of a somewhat conical shape, and the fairly thick wall presents 

 an aspect closely similar in structure to that of the preceding 

 species. 



Upon the nature of the so-called uterus different views have 

 been held by different authors. The latest view is that the organ 

 is a seminal receptacle. In a few cases in Pr. lactea this organ 

 contains spermatozoa in considerable quantity, which are enclosed 

 by coarse granules. In the case of the other species it was 



