834 NATURAL HISTORY OF AQUATIC ANIMALS. 



this region has so far afforded only a single species of true blood-sucking Leech, the Macrobdella- 

 decora of Verrill. This is, therefore, the only known Leech in our country of economic value, It 

 is very widely distributed in the Northern United States, and was at one time quite extensively 

 used by physicians. Being somewhat inferior in quality to the European Leeches, however, it 

 has, since they have begun to import the hitter regularly into this country, ceased to be consid- 

 ered as an officinal Leech excepting in a few places. 



The American Leech has, according to Professor Yerrill, a large, stout, and broad body, 

 which is considerably compressed throughout. It is strongly anuulated, and in extension is much 

 elongated, gradually tapering anteriorly. The larger specimens measure twelve inches or more 

 in length, and have a breadth of upwards of an inch. The head is rounded in front, and is 

 furnished with three stout and prominent maxillae, having the outer edge denticulate with numer- 

 ous acute teeth. The eye-spots are ten in number. The breeding season is in the spring. The 

 color above is a dark livid brown or olive green, with a median dorsal row of about twenty to 

 twenty-two bright or pale red spots, which are sometimes obsolete, and a row of rounded black 

 spots near each margin, corresponding in number, and nearly in size, with the red ones. The 

 lower surface is a bright or dark orange red or reddish brown, sometimes with black spots near 

 the margin. " This species is very common, and widely diffused in the fresh waters of the 

 Northern United States. Its range northward and southward is unknown. It is the only true 

 blood-sucking Leech known from the Northern States. It is capable of drawing blood from the 

 human skin, but ordinarily subsists upon fishes, frogs, and tadpoles. It often attaches itself to 

 the throat, and speedily kills them, even when of considerable size." 1 



While the American Leech sometimes attains a length of twelve inches, four to five inches 

 is the average adult size, and the majority of those sold in the shops measure only two to three 

 inches. American Leeches are now seldom used by physicians. The foreign species are so easily 

 obtained, so cheap, and so much more reliable in the majority of cases, that they are now given 

 the preference nearly everywhere. The American Leech was formerly extensively employed, 

 before they began to import the foreign species, and even for some time afterwards, in conse- 

 quence of the continued high price of the latter. With the gradual decline in the practice 

 of leeching the import trade in Leeches has also fallen off from year to year, the imports for the 

 past few years being less than half those for 1856, and the price about one-fourth what it was then. 



Cultivation and economic value of the American Leech. Attempts have been made to breed 

 and raise the American Leech in artificial ponds after the plan pursued in Europe, but always 

 without success. The Leeches in these inclosures have never thrived well, and, in addition, the 

 slight demand for them has tended to render all the attempts in this direction decidedly unprofit- 

 able. Mr. Herman Witte, of New York, has perhaps experimented more extensively in leech- 

 culture in this country than any other person. His ponds, constructed very much like those in 

 1'Yance, to be described further on, are located between Winfield and Newtowu, Long Island, 

 New York. They are five in number and cover an area of over fifteen acres. At present they 

 serve merely as preservative ponds for surplus supplies of imported Leeches. Other artificial 

 ponds have been started in the State of New Jersey and near Saint Louis, Missouri, but they 

 were all speedily given up. Turtles, snakes, birds, and insects were said to have destroyed great 

 quantities of the Leeches and discouraged operations. American Leeches, when they were in 

 (din mon use, were probably collected to a greater or less extent in most of the regions where they 

 were employed. Eastern Pennsylvania, Bucks and Berks Counties especially, seems, however, to 

 have furnished the principal collecting ground, in past times as at present. Numerous ponds in 



1 VEEEILL: Keport, U. S. Fish Commissioner for 1872-'73, p. 669. 



