9 6 THE LEECHES OF MINNESOTA 



Habits. This very interesting leech bears the same relation to the 

 smaller fresh water tortoises that P. parasitica does to the snapping 

 turtles and other large species. Not every tortoise is parasitized but 

 as a rule several of the leeches are found associated together on each 

 one so affected. The species also frequently occurs on the under side 

 of floating wood in ponds inhabited by tortoises. In its movements 

 it is more active than other species of Placobdella and swims with 

 much greater facility than any other, not excepting P. montifera. The 

 spermatophores and breeding habits are very similar to those of P. 

 parasitica and P. rugosa. 



Genus Hemiclepsis Vejdovsky. 



Form variable, usually rather wide and moderately depressed; 

 tissues soft and almost cedemous, translucent. Suckers as in Glossi- 

 phonia. Eyes usually four pairs, in longitudinal series near the median 

 line. Cutaneous papillae few and low. Pharyngeal salivary glands 

 diffuse; gastric caeca nine or ten pairs, branched. Genital pores as in 

 Glossiphonia, but sometimes farther apart. Chiefly free-living. 



::: Hemiclepsis occidentalis (Verrill) 

 (Plate II, fig. 12.) 



Clepsine occidentalis Verrill (1874). 



Description — This rare and very interesting leech is represented 

 in the Minnesota collection only by a batch of young, evidently re- 

 moved from the parent which carried them, and is consequently 

 described from specimens received from other localities, though the 

 anterior end of one of these young is represented in the figure. The 

 leech is of moderate size, about one and one-half inches being the limit 

 in extension. In life it is of a rather slender form, broadly rounded 

 anteriorly where there is no definitely expanded head, moderately de- 

 pressed but rather thick at the margins posteriorly and with a very 

 large caudal sucker. A noteworthy feature which separates this from 

 every other species described in this paper is the peculiar transparency 

 and gelatinous consistency of the body. 



There are four pairs of large conspicuous eyes, which cannot be 

 mistaken for the much smaller ones of Placobdella hollcnsis. They 

 are situated on somites II to V respectively ; the first pair is the 



Tlw name Protoclepsis Livanow (1002) proposed for this group is pre- 

 occupied by Protoclepsine Moore [898. 



