THE LEECHES OF MINNESOTA 103 



Genus Piscicola Blainville. 



Size small ; form slender and elongated, terete or subterete. Both 

 suckers large and explanate, the posterior usually deeply cupped. 

 Complete somites of 12-14 very short tertiary annuli. Sensillze and 

 cutaneous papillae very inconspicuous or absent. Eyes one or two 

 pairs widely separated on base of "head". Atrium simple and in- 

 testinal ca?ca nearly completely coalesced. Parasitic on fishes, but 

 often found free. 



Piscicola punctata (Verrill). 



(Plate III, figs. 21, 22) 



Ichthyobdella punctata Verrill (1871) 



Description — The usual size of this species is from 15 to 25 mm. 

 long and 2 to 3 mm. in greatest diameter, but the largest examples 

 are capable of extending to a greater length. In extension the body 

 is circular in cross section and very slender, widest at the beginning 

 of the posterior third. When contracted the distinction between 

 anterior and posterior regions of the body is much emphasized and 

 the latter becomes distinctly flattened. Although it has the form 

 characteristic of the genus the head is much smaller than in the well 

 known P. g comet ra. 



Only one pair of eyes has been detected in a large number of 

 specimens which have been received from various localities. These 

 have conspicuous pigment cups situated in somite four and conse- 

 quently correspond to the posterior eyes of P. gcomctra which they 

 resemble also in the fact that they look caudad instead of cephalad 

 as do the first pair in that species. The smaller posterior pair de- 

 scribed by Verrill I have been unable to find either in entire mounts 

 or in sections and it is possible that some of the conspicuous pigment 

 cells which are scattered through the head may have simulated eyes in 

 his living specimens. 



During life the posterior sucker is widely expanded and hemi- 

 spherical, but in preserved specimens it is always much contracted and 

 directed caudad. Just anterior to it is the minute anus among a group 

 of small wrinkled annuli. 



The genital region (clitellum) is more or less distinctly limited by 

 anterior and posterior constrictions at the furrows IX/X and 

 XII/XIII respectively. In contraction XII may be more or less re- 

 tracted within the anterior border of XIII and all three of the somites 



