THE LEECHES OF MINNESOTA 89 



XXII inclusive). In the neck-like constriction between the head and 

 body is a peculiar double annulus which is interpreted as V ai. In the 

 complete somites the three annuli increase in length caudad and aj is 

 partly cut into two by marginal furrows. Somites XXIII and XXIV 

 are triannulate at the margins only, the third annulus of each being 

 the least developed, and the furrow XXIV di/a2 deficient mesially. 

 The two following somites (XXV and XXVI) are further simplified 

 in the direction indicated in XXIII and XXIV. They are incom- 

 pletely biannulate with only traces of 0,2/013; XXVII is uniannulate. 

 Three well marked post-anal annuli form the narrow portion of the 

 sucker pedicle. 



The mouth is small in somite II ; The proboscis is long and slender 

 and the oesophagus of about equal length. There are the usual 

 seven pairs of capacious gastric caeca divided into numerous lobes 

 which reach almost to the margins of the body ; the first sends a 

 long anterior lobe forward into somite XI and the last reaches from 

 XIX to XXIII. The salivary glands are compact and rather small. 



While conforming in every important feature to the general 

 plan characterizing the other members of this genus, the repro- 

 ductive organs are somewhat peculiar in the shorter and more 

 loosely folded sperm sacs. 



The color is generally a dull greenish gray or pale olive brown 

 with an interrupted dark green or brown median dorsal line, a 

 series of obscure light yellow marginal spots or a marginal yellow 

 border, more or less interrupted on the neural annuli, and spots 

 of the same color, often including green flecks on the papillae. A 

 deeply pigmented green and brown spot marks the otherwise pale 

 colored head. The ventral surface is plain. 



Habits — This very interesting keeled leech exhibits little of 

 that marked gregariousness which is common to most other mem- 

 bers of the family. It is met with far more frequently singly than 

 in company. As a parasite it devotes itself especially to frogs and, 

 when they frequent the water during the breeding season, to toads. 



It also habitually enters the shells of living mussels, though 

 it is not known definitely that it feeds upon their soft tissues. 

 Meadow brooks and swamps adjacent to the shores of lakes and 

 ponds are its favorite haunts, where it lives among water plants and 

 beneath stones as well as upon the bodies of frogs. Nothing is 

 known of the breeding, habits beyond the bare facts that spermato- 

 pores are deposited in early spring and that the young are carried. 



