THE LEECHES OF MINNESOTA 85 



XXIV may be considered to be fully triannulate, as this furrow, 

 though not so deep as the others, is complete. The first annulus 

 (ai) is always more closely united with the second (a.?) than is 

 the third (aj). The furrows correspond closely on the dorsal and 

 ventral surfaces. Somite XXIV is usually simpler, owing to the 

 incompleteness of the furrow aiVaj toward the mid dorsal region. 



XXV is biannulate at the margins only, the furrows disappearing 

 mesiad; XXVI and XXVII are normally uniannulate. 



The small, pore-like mouth is in II. The salivary glands are 

 compact and with a median lobe. As usual in this genus there are 

 seven pairs of large spreading gastric caeca, in this species exten- 

 sively developed and reaching almost to the margins of the body 

 as fine lobes more numerous than in any other Minnesota species. 

 The last pair is the largest and reflexed as far as somite XXII. 



Small male and female orifices are located in the furrows 

 XT/XII and XII (12/(13 respectively. The testes are six pairs, the 

 sperm sacs long but closely and complexly folded in somites XI 

 and XII by the sides of the atrium. 



The coloration is very rich and striking but extremely variable. 

 The ground color of the dorsum is dull green, olive green or brown, 

 marked with bright yellow which may replace the ground color very 

 extensively. Usually the yellow is confined to the following regions : 

 — A continuous or interrupted longitudinal median band which 

 widens and narrows alternately at intervals of about three somites, 

 regular marginal spots covering the intervals between the successive 

 neural annuli, and large irregular blotches constituting an inter- 

 mediate series which often become confluent with one another or 

 with the marginal spots or both. The ventral surface is longitu- 

 dinally striped with light and dark the whole having a peculiar blu- 

 ish or purplish reflection. Dorsal integuments rather opaque. 



Habits — Living chiefly as a parasite upon the snapping turtle 

 on whose blood it feeds voraciously. The geographical range of 

 this species is largely determined by that of its principal host. As 

 the snapping turtle is an important article of commerce this leech 

 is very well known and is reported from all parts of the United 

 States. Its habits are too familiar to require description though it 

 is not so widely known that the species also lives a free life par- 

 ticularly when carrying eggs or young and feeds on aquatic worms 

 etc. 



