THE LEECHES OF MINNESOTA 123 



hard, wiry and slippery that it is really quite difficult to hold a living 

 one between the fingers. When picked up it struggles and writhes 

 violently and when disturbed creeps rapidly. It is also the most expert 

 and active swimmer of any of our common leeches. When swimming 

 it turns edgewise and undulates the body in eel-like fashion, sometimes 

 elevating the head above the surface. 



Although somewhat of a scavenger, it subsists chiefly on aquatic 

 insects and their larvae, and aquatic oligochaetes, but will attack fishes 

 and frogs or draw blood from the legs of wading boys. Not in- 

 frequently cannibalistic tendencies appear, large individuals devouring 

 the smaller ones of their own species. It is very active in seeking food 

 and will pursue its prey with considerable tenacity. 



Breeding continues over a long period — most of the spring and 

 summer. Spermatophores are formed and attached to any part of the 

 body except the anterior end which seems to be avoided. In copula- 

 tion the two leeches wind about each other and adhere by means of 

 their suckers and the exchange of spermatophores may be mutual. 

 The small, flat, amber-colored bgg cases are familiar objects to stu- 

 dents of fresh water life and are often found in great numbers attached 

 to the underside of stones etc. in the water. 



Genus Nephelopsis Verrill. 



Size large ; much depressed posteriorly. Sperm duct forms a 

 loop as in Erpobdclla; atrial cornua prominent and with a complete 

 spiral turn. All annuli of complete somites more or less distinctly 

 subdivided. 



Nephelopsis obscura Verrill. 

 (Plate V. figs. 35, 36; Plate VI. fig. 40) 



Nephelopsis obscura Verrill (1872). 



Description — Like the species last described this is a rather large 

 leech, attaining a length nearly equal to Erpobdclla punctata and con- 

 siderably exceeding it in the breadth of the posterior region of the 

 body. Compared with other species of the family belonging to the 

 Minnesota fauna the body is more depressed and in its posterior part 

 very much broader than they. The margins are sharp and prominent. 

 The region anterior to the clitellum is relatively slender and sub- 

 depressed with rounded margins. Texture hard and firm. 



Nothing characteristic appears in connection with the mouth and 

 lip which is rather broad. There are four pairs of eyes of about equal 



