Fig. 348e.—Hirudo medicinalis. a, anterior end, with open buccal cavity, with the jaws, J, at the; b, one jaw isolated. (After Claus.)
Hirudo medicinalis, L., 1758.
It occurs in numerous colour varieties, one of which has been designated Hirudo officinalis, Moq.-Tandon. Usually the dorsal surface is greyish-green and is marked with six rusty-red longitudinal stripes. The ventral surface is olive-green, more or less spotted with black, and marked at the sides with a black longitudinal line. The length averages 8 to 12 to 20 cm. This leech lives in swamps, ponds and brooks, overgrown with plants and having a muddy bed. The cocoons are deposited in the soil at the sides. Europe, as well as North Africa, is its home. At the present day it has been exterminated from most parts of Central Europe, but it is still very common in Hungary. Its use for medicinal purposes is well known. A large leech can suck about 15 grs. of blood, and about the same amount is lost through secondary hæmorrhage.
Hirudo troctina, Johnston, 1816.
Syn.: Hirudo interrupta, Moq.-Tandon, 1826.
This species measures 8 to 10 cm. in length. The back is greenish, with six rows of black spots surrounded by red; the lateral borders are orange-coloured; the abdomen spotted or unspotted. Its habitat is in North Africa and Sardinia. It is applied medicinally in England, Spain, France, Algeria, etc.
Genus. Limnatis, Moq.-Tandon, 1826.
Nearly related to Hirudo, but is differentiated by a longitudinal groove on the inner surface of the upper lip of the anterior sucker. The jaws are furnished with over 100 very sharp toothlets.