30 ON A NEW SPECIES OF ENTEROPNEUSTA, 



rounded cells lying in-egiilarly internal to the limiting meml)rane 

 in young gonads doubtless belong to it. In the young gonads 

 there is present a distinct central cavity filled up in some cases by 

 a deeply staining homogeneous substance. As in the other species 

 of Ptychodera, the gonads contain large nunil)ers of rounded or 

 cubical masses of a peculiar substance which in the sexually 

 immature animals fills up the gonads almost completely. It is 

 found in the young gonads, both male and female, but it persists 

 for a much longer time in the case of the ovaries than in the 

 testes. Even in the mature ovaries traces of it remain, while in 

 the mature testes no trace of it is left. Spengel regards this 

 substance as nutritive in function, and the presence of tlie 

 abundant deutoplasm in the ova readily accounts for its greater 

 })ersistence in the ovaries. 



The ova of this species are essentially similar to those oi Ft. 

 oninuta. They average about -^ nun. in diameter, and 

 possess very abundant granular deutoplasm. The gei-minal 

 vesicle is very large, and contains a spongy nucleoplasm in which 

 there is situated one large nucleolus and several smaller masses. 

 The ripe ovum is invested in a thick egg membrane attached to 

 which there may be a few very small flattened nuclei apparently 

 representing the follicular layer. The heads of the ripe sperma- 

 tozoa are somew^hat ovoid or rounded in form, and the flagellum 

 is ver}'' long and slender (fig. 26). 



H&patic region : With the exception of the presence of two 

 ciliated bands in the gut, Spengel's description of this region in 

 I't. minuta applies generally to that of this species. The li\er 

 sacs (fig. 2-4, /<'?w.) communicate with the gut by narrow transverse 

 clefts bounded by anterior and posterior lips. The wall of the 

 gut is thrown into obli((uely transverse folds which are interrupted 

 on the dorsal side by the two longitudinal grooves, while a well 

 marked furrow^ occupies the median dorsal region of the gut. 



The liver sacs are lined by a layer of close-set long narrow cells 

 with long nuclei in a row near their base (fig. 24, ehep.). The 

 cells contain numerous yellowdsh-brow^n granules, which also occur 

 less abundantly in the somewhat shorter but otherwise similar 



