170 
The British Leeches 
The blackish green pigment generally prevalent on the dorsal sur¬ 
face of adults is more soluble in alcohol than the black markings which 
it frequently obscures. In specimens which have been submitted to 
prolonged immersion in alcohol it becomes entirely dissolved and the 
primitive pattern again is rendered more or less evident. Blanchard 
(1892 e, p. 3, fig. 1) gives a figure of an adult specimen of this kind 
in the Dresden Museum, in which the pattern is almost perfectly 
preserved. 
Confusion of species. Moquin-Tandon confused the species now 
under consideration with Limnatis nilotica, Savigny, 1822. In the two 
editions (1826 and 1846) of his classical monograph we have a far from 
adequate description of Limnatis nilotica and also what is, in its essential 
characters, nothing more than a second description of the same species, 
Fig. 12. Side view of head region in Hirudo medicinalis and Haemopis sanguisuga. 
Somites numbered in Boman figures, Bings in italics. The eyes are indicated by 
black dots. 
under the names Haemopis vorax, 1826, and Haemopis sanguisuga, 
1846. When therefore this writer turns to the true Haemopis sangui¬ 
suga it becomes necessary to provide for it a new name, and accordingly 
he establishes for its reception a new genus Aulastoma (1826) and, in 
the second and best known edition of his work (1846), we find it de¬ 
scribed as A ulastoma gulo. 
Thus arose the erroneous idea that Aulastoma gulo and Haemopis 
sanguisuga were two distinct species. 
Whitman (1886) and Apathy (1888 a) rejected Haemopis sanguisuga 
as described by Moquin-Tandon, but it remained for Blanchard (1894 b, 
p. 43) to give a complete solution of the difficulty. 
