262 A MONOORAPH OF THE AUSTRALIAN APHRODITEA, 



rosettes of cilia are represented as canals leading from the cavity 

 of the cfecum to the exterior. 



The true position of the segmental organs of PoJy7ioe is very 

 different from this. On the ventral surface of the body close to 

 the base of each parapodium is a smooth elevation, the integument 

 of which is very richly provided with vermiculate and flask-shaped 

 subcuticular glands. At the posterior and external angle of this 

 elevation is a process, the ventral tubercle. The only statement 

 which"! have met with regarding the nature of this tubercle is a 

 conjecture by Prof. Huxley {Anat. of Invert, j). 231), that it may 

 possibly be connected with the reproductive function. It is of 

 varying shape ; in some species short and vase-like with longi- 

 tudinally folded walls; in Aniinoe prcBclara, A. Wahlii and 

 Thormora argiis, in which I have studied it more specially, it is a 

 cylindrical, smooth, cirriform process, sometimes a third of the 

 length of the ventral cirrus. It is traversed by a canal with 

 dilatable ciliated walls, which opens at its extremity either by a 

 rosette of several mouths or by a single orifice. This canal is 

 continued from the base of the process inwards and slightly 

 forwards and ends in the body cavity at some distance from the 

 middle ventral line. The walls of this inner portion of the canal 

 are glandular and contain reddish-yellow bodies, some of which 

 may, on the application of slight pressure, be seen to pass out 

 through the external aperture. Tliese bodies are of a quite 

 different appearance from the concretions observable at the bases 

 of the tentacles and cirri, they are clearer, browner and seem to 

 be semifluid. Of the form of the internal extremity of the canal 

 I did not succeed in satisfying myself ; but there is no doubt 

 that it opens freely into the perivisceral cavity. I found in one 

 specimen spermatozoa in the act of being discharged through 

 this canal. They passed along the canal by the action of the cilia 

 in considerable numbers, and were driven into the outer portion, 

 which became in some cases slightly distended with them, and 

 passed gradually out at the external orifices. In the female the 



