The Hirud'mea of Illinois. 527 



ridges extending throughout its entire length. The pharynx 

 reaches into somite X. 



Along narrow straight stomach reaches to XIX, where a 

 pair of large lateral cajca arise and pass caudad to XXII or 

 XXIII. Along the course of the stomach are numerous 

 small lateral c<eca, as many as two or three pairs per somite ; 

 and just posterior to the origin of the large posterior pair are 

 two or three pairs of quite large, short, globular caeca which 

 extend laterad dorsal to the principal cxca. 



Color. — Many color varieties of this species occur, some of 

 which have been indicated by Yerrill ('74); but only the 

 blotched kinds are represented in the Illinois collection- 

 During life the ground color in such is generally some shade 

 of olive-green or greenish brown, blotched with irregular 

 intermixed spots of lighter grays and darker browns and 

 black. The former kind are likely to predominate on the 

 ventral side, from which the darker pigments may be alto- 

 gether absent. The darker markings may be scattered and 

 distant or so close as to become confluent and give to the 

 animal an almost black color. Most of the Illinois examples 

 are only moderately blotched. Preservation always causes 

 the loss of the green pigments. No metameric features have 

 been detected in the pigmentation of this species, nor is there 

 any evident close relation between the disposition of the pig- 

 ment and the arrangement of the muscles. 



Habits. — In the neighborhood of Philadelphia this so- 

 called horse-leech lives in the mud by the sides of pools, 

 ditches, and streams. At times it leaves the water in search 

 of earthworms, which constitute part of its food. Various 

 kinds of aquatic insects and their larvie, aquatic oligochaetes, 

 gastropods, and lamellibranchs are eagerly eaten, and large 

 quantities of mud containing organic matter are swallowed. 

 When the opportunity arises this leech will take blood, 

 attaching itself to drinking cattle or to the legs of boys 

 wading in its haunts. 



