126 RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 



such as Zizania aqiiatica, Scirpiis Jhiviatilis, Sagittaria, Sparganium, 

 &c. When disturbed the animal receded from its position of rest 

 and swam rapidly like the ordinary medicinal leech, Hirudo decora. 

 It appears to belong to a different genus from the latter, and ap- 

 proaches most in character Nephclis, though it even exhibits points 

 of difference from this as ordinarily described. The more mature 

 animal from the Beverly pond may thus be characterized : 



Body elongated, flattened cylindroid, narrowing anteriorly, 

 smooth, indistinctly annulated, margin acute, above blackish oliva- 

 ceous, below translucent grayish, with a more or less reddish tinge 

 due to the blood. No .stri?e or markings visible beneath, and the 

 annuli in this position scarcely perceptible. Annuli about 98, 

 above minutely punctated with yellowish olivaceous or dusky 

 whitish, and narrowly defined by the same hue. Head continuous 

 with the body, obtuse. Mouth large, obliquely terminal, sub-bi- 

 labiate : lower lip crenulate. Jaws three rudimental folds without 

 teeth. CEsophagus capacious, with three longitudinal folds. In- 

 testine simple. Anus dorsal, conspicuous, in the penultimate anuu- 

 lus. Eyes six ; anterior pair largest and approximated ; second 

 pair in second annulus corresponding with the lower lip ; third 

 pair smallest, more deeply situated than the others, 'and placed 

 slightly external and posterior to the second pair. Acetabulum 

 terminal, inferior, circular, nearly as wide as the body. The larger 

 male aperture conspicuous, and situated about one-fifth of the length 

 of the body from the head ; the smaller female aperture scarcely 

 visible and situated two or three annuli back of the former. Ivcngth 

 to 2>^ inches by two lines wide; by contraction becoming shorter 

 and wider. 



Smaller specimens, from half an inch to an inch in length, from 

 the ditches communicating with the Delaware and Schuylkill rivers, 

 and from the latter agree in form and constitution with the preced- 

 ing, having the same number of annuli to the body and the same 

 number and disposition of the eyes. The color is translucent pale 

 Indian red, passing into darker shades and without the colored 

 punctse. Some young pale individuals exhibit a few scattered 

 minute black punctae down the back, due to single pigment cells, 

 but mostly these are absent. Intermediate sized individuals from 

 the Delaware and Schuylkill exhibit a gradation of character be- 

 tween the two forms indicated. Further numerous young from the 

 ditches, kept in an aquarium for the last month, have gradually 

 assumed the appearance of the more mature animal as first de- 

 scribed. 



