TYPHLORHYNOHUS NANUS. 645 



parenchyma J and has its wider end next the ovary (fig. 8, 

 R. s.). In the space enclosed by this body, which may be 

 called the receptaculum seminis, lies a small mass composed 

 of spermatozoa (fig. 8, 8.), which are thus immediately in 

 front of the ripest, most anterior egg. 



There is a pair of unbranched yolk glands which extend 

 from the level of the front end of ovary as far forward as the 

 pharynx, lying close along the lateral wall of either side of 

 the body in a cavity of the parenchyma, which here is not 

 much developed. 



These yolk glands are built up of elongated cells lying 

 parallel to one another and closely pressed together, with their 

 long axes roughly dorsiveutral. Each cell has a nucleus at about 

 its middle ; each nucleus contains a nucleolus lying in a clear 

 space in the centre of the nucleus, surrounded by a finely 

 granular ring when seen in section. In each cell are two, 

 three, or several small black refriugent bodies, which tend to 

 group themselves together in a ring. Amongst these black 

 bodies are found small refringent yellow globules of yolk 

 matter. 



The female aperture is furnished with a sphincter muscle 

 arrangement (fig. 7, B'p.), and opens into a small chamber 

 (fig. 7, B. s.). The ciliated epidermis of the body- wall 

 extends to the walls of this chamber. Into it the bursa 

 seminalis (fig. 7, B. s.) opens dorsally through a narrow neck. 

 Above the neck, which is quite short, the cavity is transversely 

 widened, but narrow antero-posteriorly, Dorsally it extends 

 to a point just below the front end of the ovary, but does 

 not cominunicate with the latter directly. The cavity is 

 bordered by a chitinoid lining substance which stains deeply ; 

 beyond this lining the walls are built up of clear hyaline 

 protoplasm, which merges quite gradually with the proto- 

 plasm of the parenchyma. A small number of muscle-fibres 

 lie in the walls of the bursa, running from the neighbourhood 

 of the neck of the cavity to the body-wall, or in some cases to 

 the capsule of the penis (fig. 7, M.). The hinder wall of the 

 bursa at about its middle is produced to form a kind of spout 



