316 



APPENDIX. 



leave the pouch, and return again to their shelter. This singular 

 fact appears to have been first noticed by Henry Baker. 



Glossiphonia heteroclita (page 52). 



Blainville says that this is undoubtedly a variety of G. sexoculata, 

 or rather younger individuals, — an opinion which Brightwell's figure 

 seems to confirm. Moquin-Tandon says that it is less than G. sex- 

 oculata, less crustaceous, more extensile and transparent, and not so 

 inactive, — all qualities in agreement with Blainville' s view ; and when 

 he tells us that the eyes, excepting the front ones, are set wider 

 asunder, he lets us know that this is apparently so ; and it is surely 

 a character of no importance, were it a fact. 



Grlossiphonia bioculata (page 52). 



Hab. Lakes, ponds, and ditches, "and in places with but little 

 water, lurking under stones, and especially beneath the bark of 

 decaying trees and branches, where its abode is permanent." — 

 Dalyell. 



This is a smaller and rather more active species than G. sexocu- 

 lata. Sir J. G. Dalyell says, *'it feeds on the vegetable matter 

 among which it dwells, and it likewise consumes fish." There is no 

 doubt that, when unconfined, it preys on living animals, sucking 

 their juices ; and Sir J. G. Dalyell indeed ascertained that the ver- 

 milion-coloured larva of a dipterous fly was the favourite victim. 

 *' When the prey was introduced to vessels containing the leeches, they 

 raised themselves on the sucker, as if surveying around ; then some 

 one bolder than the rest advanced, endeavouring to affix itself to the 

 victim, which being effected, the position was pertinaciously main- 

 tained in spite of its writhing and struggles. Should such an attack 

 occur at night, an empty, brown, transparent skin, scarcely visible, 

 is all that remains of the prey in the morning, while the intestines 

 of its enemies are seen replete with the red substance that constituted 

 the body. It is singular how the fleshy matter of the prey is ex- 

 tracted, while the integument is left quite entire." 



The pulmonated mollusca are not less acceptable to this leech. 

 Miiller gives us an account of what he witnessed {Miiller's Verm. 

 ii. 41). 



I have not seen a specimen that exceeded an inch in length, and 

 it is narrow proportionally when extended. It is of a grey colour, 

 speckled, with a fascia along the back paler than the rest of the 

 body, and which loses itself before it reaches the tail. The body 

 enlarges from the head backwards, and is bulged behind, subcylin- 

 drical, distinctly ringed, and hence the sides are neatly crenulated. 

 Although almost semitransparent, no interranea are visible, unless 

 when the leech has been recently gorged with food. There is a 

 series of small sharp granules on each ring. Head colourless, with 



