Anatomical structure of Aspidogaster conchicola. 527 



reaching to complete embryonic development and after the processes 

 of reproduction have been for a long time continued, there may still 

 be a considerable mass of spermatozoa waiting at this place. For 

 the sustenance of these it seems probable that the prostate glands 

 may be destined, whose secretion may, at the same time, supply a 

 fluid for the floating along of the sperm cells, or a medium for the 

 action of their own flagellar organs. I have never found masses of 

 sperm passing along the oviduct, but there may be small additions 

 continually supplied from the vesicula seminalis. The general ap- 

 pearance of the distended organ, as well as its fine structure, com- 

 pletely agree with the seminal vesicle. 



From this onwards the oviduct, through all its extent till it 

 reaches the vicinity of the vagina, has a uniform structure. Between 

 the eggs or groups of eggs it contracts and its walls then are thicker 

 with here and there a nucleus to be seen. In this long canal the 

 eggs are held until their contained embryos are ready to hatch, so 

 that it is fittingly called the uterus. 



The uterus increases somewhat gradually its musculature and 

 forms a thick-walled anterior end which is at least as long as the 

 vagina. Its circular and longitudinal muscles are thick fibres that 

 hold the eggs back or press them through into the vagina. This 

 lies to the left of the penis apparatus but its posterior end may be 

 found bent or, partaking of the nature of the uterus, coiled and 

 higher dorsalwards than the penis-sack. Very strong inner circular 

 muscles in a single layer and outer longitudinal muscles (Fig. 2 VM) 

 in many layers characterize it, and on the inside is a layer of con- 

 siderable thickness, exhibiting no nuclei nor cellular structure but 

 which must be of epithelial nature. In the living animal I have not 

 seen it, on account of the non-transparency of this part, and in my 

 sections it is broken up transversely and ragged. It is present all 

 the way through to the thin-walled uterus. 



Round the vagina is a mass of cells that apparently present the 

 same relations to the vagina as the prostate glands do to the penis. 

 In the character of the cells and manner of staining too, these two 

 masses present close affinities but the former seems to be far less 

 ditferentiated than the latter. Its cells are small and pressed extremely 

 tightly together, nuclei numerous except in a layer close round the 

 vagina, which however betrays no indication of ducts. Anteriorly they 

 are continuous with subcuticular-like cells, which, on the side next 

 the penis are reflected onto the penis-sack as far as to the prostata. 



