Chap. XIIL] 



LEECHES. 



483 



the march of troops in the mountains, when the Kan- 

 dyans were in rebellion, in 1818, the soldiers, an^ 1 

 especially the Madras sepoys, with the pioneers ud 

 coolies, suffered so severely from this cause that numbers 

 perished. 1 



One circumstance regarding these land leeches is re- 

 markable and unexplained ; they are helpless without 

 moisture, and in the hills where they abound at all other 

 times, they entirely disappear during long droughts ; — 

 yet re-appear instantaneously on the very first fall of 

 rain ; and in spots previously parched, where not one 

 was visible an hour before, a single shower is sufficient 

 to reproduce them in thousands, lurking beneath the 

 decaying leaves, or striding with rapid movements 

 across the gravel. Whence do they re-appear ? Do 

 they, too, take a " summer sleep," like the reptiles, 

 molluscs, and tank fishes ? or may they, like the Roti- 

 fera, be dried up and preserved for an indefinite period, 

 resuming their vital activity on the mere recurrence of 

 moisture ? 2 



Besides a species of the medicinal leech, which 3 is 



1 Davy's Ceylon, p. 104 ; Mar- 

 shall's Ceylon, p. 15. 



2 See an account of the Botifera 

 and their faculty of repeated vivi- 

 faction, in the note appended to 

 this chapter. 



3 Hirudo sanguisorba. The 

 paddi-field leech of Ceylon, used 

 for surgical purposes, has the 

 dorsal surface of blackish olive, 

 with several longitudinal striae, more 

 or less denned ; the crenated 

 margin yellow. The ventral sur- 

 face is fulvous, bordered laterally 

 with olive ; the extreme margin 

 yellow. The eyes are ranged as 

 in the common medicinal leech of 



Europe ; the four anterior ones 

 rather larger than the others. The 

 teeth are 140 in each series, ap- 

 pearing as a single row; in size 



dorsal, ventral. 



diminishing gradually from one 

 end, very close set, and about half 

 the width of a tooth apart. When 

 lull grown, these leeches are about 



I I 2 



