SCT,EROSTOMA. 



87 



chitinous lips ; but tlie conspicuousness of the latter became mucli 

 lessened after the specimens had been placed in spirit (2, fig. 22). 

 In both sexes the surface of the body is quite smooth ; but the 

 female displays a series of spirally arranged lines, which at first 

 sight convey the idea of a natural twisting of the body ; this 

 torsion, however, is more apparent than real, being likewise more 

 marked in some individuals than in others. The body of the 

 female, towards the tail, exhibits a decided tendency to fold upon 



Fig. 22. — Selerostoma syngamns, Diesing. — I.Male and female ; natural size. 2. Upper part of the 

 same, showing more especially the six-lobed circular lip of the female, and the mode of 

 sexual union ; enlarged. 3. Lower end of the body of tlie female, with its mucronate 

 caudal appendage ; enlarged. 4. Lower end of the body of tlie male, inverted to show 

 the cup-shaped bursa, hard rays, lateral muscles, bifurcate penis, digestive tube, and 

 rounded tail; magnified 30 diam. 5. Mature egg; X220diam. 6. Egg, with contained 

 embryo ; X 220 diam. — Original. 



itself; and in one example this feature was very significant 

 (3, fig. 22). The lower part of the body preserves a tolerably 

 uniform tliickness almost to the extremity, where it is suddenly 

 constricted to form a short, narrow, mucronate, pointed tail, 

 scarcely visible to the naked eye. Employing a pocket lens, it is 

 easy to observe through the transparent integument the spacious 



