790 PROFESSOR J. STEPHENSON 



spermathecal apertures ; but dorsally it ceases some distance behind the level of 

 septum 4/5 , and includes not more than the posterior two-thirds of segment v. 



The testes had disappeared. A quantity of spermatozoa were free in segment v ; 

 and other masses were contained in the sperm-sac, derived from septum 5/6, which 

 extended backwards through the sixth, or sixth and seventh segments. The back- 

 ward extent of the sperm-sac therefore is, at least in the specimens examined, less 

 than in many Naididse ; here the enormous mass of yolk-matter in the ovisac has the 

 appearance of preventing any further extension of the sperm-sac. 



The funnels are of considerable size, cup-shaped, with a thickly ciliated margin 

 composed of elongated columnar cells ; they face forwards in segment v. The vas 

 deferens, piercing septum 5/6, has a comparatively wide lumen, and after forming a 

 downward loop enters the atrium on its dorsal aspect. The atrium is a large globular 

 chamber, in segment vi, with moderately thin walls composed of a single layer of 

 cubical cells and a thin muscular investment, outside which the peritoneum is indi- 

 cated in sections by a few scattered nuclei ; there are no glandular cells in connection 

 with vas deferens or atrium. The atria seem regularly to contain masses of 

 spermatozoa. 



The ej aculatory duct is slightly invaginated upwards into the atrial chamber ; it 

 is short, not more than half the height of the atrium in length ; its lumen is narrow 

 and circular ; outside the epithelial lining is a coat of circular muscular fibres, and 

 external to this a thick investment of small peritoneal cells, each cell consisting of 

 little except a nucleus. Also to be distinguished around the duct are a number 

 of elongated or stalked cells, possibly glandular and belonging properly to the 

 epithelial layer of the duct. 



The male aperture occupies a position corresponding to that of the ventral setal 

 bundle of segment vi ; there are no genital or other setse in this position. 



Ovaries and ovarian funnels were not seen ; and the female organs were 

 represented in these specimens only by the ovisac, originating from septum 6/7 and 

 stretching back through segments vii-x. This seems to be filled, in the specimens 

 examined, by one huge egg, of an elongated and rather sausage-shaped form corre- 

 sponding to that of the sac — or at any rate by an aggregate of yolk-granules such as 

 are commonly seen in the ova of the Naidid£e. These yolk-granules may 'even be 

 seen in segment vi, extending forwards as far as the posterior surface of the atrium. 



The spermathecas are in segment v — large ovoid sacs, with thin walls, the 

 epithelial layer of which is composed of rather flattened cells ; in places the flattening 

 may go further, and the wall may be much attenuated. A thin muscular coat can be 

 made out in places. Their bulk, and the bulk of the atria behind them, may cause 

 the spermathecae to be displaced forwards, so that they appear in front of the 

 clitellum ; and, indeed, by causing a forward bulging of septum 4/5 they may even 

 reach the level of the setse of segment iii. They contain masses of spermatozoa, not 

 spermatophores. The spermathecal duct is narrower at its aperture than above 



