NATURAL SCIENCES OF PHILADELPHIA. 229 



The following gentlemen were elected correspondents : L. E. 

 Lateraer, M. D., of New York ; A. A. Breneman, of Lancaster ; 

 H. Evan Rijgersma, of St. Martin's, W. I.; Prof Oliver W. 

 Holmes, of Boston. 



On favorable report of the Committees, the following papers were 

 ordered to be published : 



Notice of some American LEECHES. 

 BY JOSEPH LEIDY, M. D. 



Having been invited by Mr. R. H. Lamborn, Secretary and Treasurer of the 

 Mississippi and Lake Superior Railroad Company, to join an excursion to Min- 

 nesota andtiake Superior, the last summer, during the trip I had the opportu- 

 nity of making many interesting observations in natural history. Tlie many 

 lakes of Minnesota are rich in raoUusca, annelides, &c. Among the anne-« 

 lides, besides an abundance of the ordinary American medicinal leech Jlirudo 

 decora., I noticed one which struck me from its general resemblance to a variety 

 of the European medicinal leech, II. 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 succeeed in getting the animal to do so. Upon exami- 

 nation of the leech, I find it belongs to a different genus from Hirudo, appar- 

 ently to the genus Aulastomum. Its characters are as follows : 



AULASTOMUM LACCSTRIS, n. S. 



Body cylindroid, compressed, narrowing anteriorly, obtuse at the sides (in 

 movement more cylindroid, or less flattened, and quite obtuse laterally com- 

 pared 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. NLnety-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 

 obliqut'ly terminal, large. Acetabulum subbasilar, ventral, sessile, circular. 

 Anus dorsal, above the acetabulum. Male aperture in the 24th annulus (but 

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

 (apparently between 28th and 29th). Oesophagus 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 mucus membrane. Teeth 12 in number 

 to each jaw, bilobed at base. Length 4 to 5 inches, breadth 5 lines posteri- 

 orly ; acetabulum 2 lines in diameter. 



§1 Var. An individual of lighter olive green than the former had black macu- 

 lae replacing the dark green ones, which were also more distinct and fewer. 



Specimens described from Twin Lake, Minnesota. In the summer of 1865 

 I saw several leeches at Saut St. Marie, in Lake Superior, 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 mar- 

 gins of the latter projected branching processes curling at the ends. 



Notwithstanding our familiarity with the American medicinal leech, its long 

 and frequent employment in the medical profession, and the vast numbers 

 which have been brought to notice, it has been so imperfectly described that, 

 in the excellent Systema Helminthum of my late esteemed friend Dr. Diesing, 

 of Vienna, it has been placed with the " Bdellidea S[)ecies genere penitus 

 dubiifi." I therefore take the present opportunity of indicating its characters 

 more fully. It agrees most nearly with the diagnosis of the genus Hirudo, of 



1868.] ♦ 



