332 



AUSTRALIAN HIRUDINEA, I., 



the ventral lacuna becomes much wider owing to the disappear- 

 ance of the dorsi-ventral muscles. 



The ovaries are large hollow 

 sacs lying in certain regions 

 in the large ventral lacuna, 

 in other regions in the late- 

 ral portions of this lacuna 

 according as the dorsi-ventral 

 muscles are absent or present. 

 Each ovary consists of three 

 pouches, the first pair of 

 which arises at its anterior 

 extremity. These pouches 

 are compressed antero-pos- 

 teriorly, and appear oblong 

 in transverse sections. They 

 lie in lateral horns of the 

 ventral sinus. The second 

 pair of pouches lies in the 

 median sinus itself, and resem- 

 bles the anterior pair except 

 that the pouches are smaller. 

 The third pair of pouches 

 constitutes the main portion 

 of the ovaries. Whereas in 

 the first and second pairs the 

 wall is quite regular in out- 

 line, in the third pair the wall is much folded and irregular 

 in outline. They arise at the point at which the proboscis passes 

 into the oesophagus, and extend as far as the stomach. The 

 ventral lacuna is here enormously developed, the dorsi-ventral 

 measurement representing fully one-half the thickness of the 

 section. The ovaries in this region, when the ova are stained 

 with hematoxylin, form the most imposing structures in the 

 body. The right ovary extends for some distance beyond that 

 on the left side. They do not lie symmetrically, the right ovary 



Fig. 4. — Glossiphonia australiensis, sp.n. 

 Diagram of female organs. 



