470 AUSTRALIAN HIRUDINEA, III., 



The oral sucker is constituted by eight annuli, the eighth 

 forming its lower lip. The mouth lies slightly anterior to the 

 central point of the oral sucker, in the posterior region of 

 somite iii. The posterior sucker, as in most species, is slightly 

 longer than broad. The anus lies between the second and third 

 last annuli. 



In one specimen two i)airs of eyes were made out, and in the 

 other an unpaired eye(?) was present in addition to these. Tlie 

 paired eyes lie on the posterior region of annulus 5, and the 

 anterior region of annulus 6; that is, in somites iv., and v., 

 respectively. The unpaired eye(?) was made out to the right side 

 of the median line, and lay partly on annuli 3 and 4. The first 

 paired eyes which the unpaired eye represents(?) are evidently 

 undergoing degeneration as regards pigmentation. 



In the case of the specimen in which the eye in an unpaired 

 condition was not seen, examination of sections failed to show 

 any trace of an ocular structure in the position occupied by it in 

 the other specimen. We may then take it as granted that tlie 

 characteristic number for the species is four. It would seem 

 ])robable, further, that the apparent ocular organ between annuli 

 3 and 4 is not in reality an eye, although much resembling the 

 same, on external examination, as regards shape and pigmentation. 



Digestive system. — In general this system bears close resem- 

 blance to that of G. heteroclita and G. australiensis. The mouth 

 is situated in annulus 4, anterior to the mid-point of the oral 

 sucker. The proboscis extends from the seventh postoral annulus 



