RESEARCHKS IN HELMINTHOLOGY AND PARASITOLOCxY. II9 



during the trip I had the opportunity of making many interesting 

 observations in natural history. The many lakes of Minnesota are 

 rich in mollusca, annelides, &c. Among t^e annelides, besides an 

 abundance of the ordinary American medicinal leech Hiriido decora, 

 I noticed one which struck me from its general resemblance to a 

 variety of the European medicinal leech, H. medicinalis. One of 

 the gentlemen in company with us, Mr. Clark, allowed me to try 

 upon him its disposition to bite, but I did not succeed in getting the 

 animal to do so. Upon examination of the leech, I find it belongs 

 to a different genus from Hirudo, apparently to the genus Aulasto- 

 miini. Its characters are as follows : 



Aulastoviian Lacustris, n. s. Body cylindroid, compressed, nar- 

 nowing anteriorly, obtuse at the sides (in movement more cylindroid 

 or less flattened, and quite obtuse laterally compared with Hirudo 

 decora in the same condition). Color throughout olive green (with 

 more of a yellowish hue than in the dorsal green of //. decora), 

 closely maculated everywhere with confluent spots of a darker hue 

 of the same color. Ninety-two annuli, exclusive of the lips, of 

 uniform width, smooth. Upper lip half ovate, obtuse ; lower lip 

 narrow. Eyes ten, eight in the upper lip, the last pair .separated 

 by an annulus from the others. Mouth obliquely terminal, large. 

 Acetabulum subbasilar, ventral, sessile, circular. Anus dorsal, 

 above the acetabulum. Male aperture in the 24th annulus (but ap- 

 parently between the 23d and 24th). Female aperture in the 29th 

 annulus (apparently between the 28th and 29th). CEsophagus 

 capacious, extending to about the 22d annulus, with 12 folds. Jaws 

 three, small, when at rest included in pouches formed by an eversion 

 of the mucous membrane. Teeth 12 in number to each jaw, bilobed 

 at base. Length 4 to 5 inches, breadth 5 lines posteriorly ; acetab- 

 ulum 2 lines in diameter. 



Var. An individual of lighter olive green than the former had 

 black maculae replacing the darker green ones, which were also more 

 distinct and fewer. . 



Specimens described from Twin Lake, Minnesota. — In the sum- 

 mer of 1865 I saw several leeches at vSault Ste. Marie, in Lake Supe- 

 rior, which, so far as I can remember, were of the same species. 

 At the edge of the shore I also saw some cocoons which I supposed 

 to belong to the same animal. They were ochreous yellow, oval, 

 about 4 or 5 lines in diameter ; the surface impressed with concave 

 pentagonal and hexagonal pits. From the angles of the margins of 

 the latter projected branching processes curling at the ends. 



Notwithstanding our familiarity with the American medicinal 



