CONTRIBUTIONS TO THE ANATOMY OF THE HIRUDINEA. 473 



system, but this has not become quite closed, and remains in 

 connection with the coelom. 



The botryoidal and other capillaries present considerable 

 difficulty, and their consideration is best deferred until after an 

 examination of the other genera of the Gnathobdellidse. 



Two other liquid-holding spaces occur in Hirudo, which, I 

 think, possess great interest. 



The ovaries are filamentous bodies with a club-shaped ter- 

 mination ; the round bodies seen in connection with the ovi- 

 ducts, and usually termed ovaries, are in reality merely sacs 

 containing the true ovaries, and also a fluid devoid of hsemo- 

 globin, but containing amoeboid corpuscles. What are these 

 corpuscles ? I regard them as primitive blood-corpuscles, 

 similar to those found in the Rhyncobdellidse, and although, of 

 course, until we have some direct observations made upon the 

 embryo, it is a mere conjecture, I expect that the oviducts 

 possess at one period open mouths, opening into a coelomic 

 space, which contains amoeboid corpuscles, and that they 

 close around the ovaries before hsemoglobin is developed. This 

 theory receives great support from the fact that in Clepsine, 

 Pontobdella, and Branchellion, the ovaries lie in the ven- 

 tral sinus, which contains, in common with all the blood-spaces 

 in these genera, amoeboid corpuscles. 



I have not at present specially studied the generative organs 

 in the group, but I think that even in the genera above men- 

 tioned the oviducts have acquired a connection with ovary, and 

 that having primitively open mouths similar to those of the 

 Chsetopoda, these have become closed around the ovary. 



The other space in Hirudo which it seems to me may have 

 a similar morphological significance, is a sinus around the vas 

 deferens. 



In Pontobdella the vas deferens is an exceedingly fine canal 

 with ciliated walls. In Hirudo it is apparently of considerable 

 size, but on further examination the actual canal is found to be 

 exceedingly narrow and a sinus is found around it packed with cells 

 which possess rather a degenerate appearance but are very similar 

 to the amoeboid cells found in the periovarian sinus. No sinus 



