78 ' [April. 



were full-grown), until the end of May, or in two generations, 

 though the latter seems iniprol>able. 



The above notes have been abbreviated from my diary, and 

 the following conclusions may be drawn from them : The young 

 larvae enter the pulmonary orifice, and burrow in the mantle, 

 eventually reaching the liver (v. figure). 



They inconvenience the host, but to what extent I do not fully 

 know. Possibly, if they enter when very young, and grow with 

 the snail, the latter would not notice them so much as when a 

 half-grown larva penetrates the mantle cavity. In the latter case 

 the snail promptly leaves the water. All those snails which I have 

 collected from above the water were infected, but infected snails 

 can also be found below the surface. A careful examination will 

 reveal the red larva through the shell. Whether the snail is 

 necessary to the growth of the larva, either throughout life, or at 

 particular periods, or at all, can only be determined by breeding. The 

 snail does not appear to be deformed or dwarfed. 



This case of parasitism has not, I believe, been noticed before ; 

 why, it is difficult to see, perhaps because dipterologists have 

 overlooked such an unlikely habitat for laiwse, and also because 

 the majority of conchologists are not also malacologists and 

 dissectors. Still it is surprising ; and it is to be hoped that 

 during the coming spring some London entomologist will thoroughly 

 work out the life history of this interesting Chironomid. 



Finally, I may mention that the larva is characterised by red 

 l>lood, green granules in special cavities (v. Miall and Hammond), 

 first joint of the antennae bearing a setiform process equal in length to 

 the remaining three joints, no ventral tubules, two dorsal papillae 

 bearing bunches of hairs, and two papillae below them at the anal 

 end (v. figures). 



The pupa has a fringed tail-plate and respiratory bunches. In 

 these points this species seems to agree with Chironomtis niveipennis 

 (y. Miall and Hammond, p. 11). 



Etwas, Farnham, Surrey : 



Januarij Ji\st, 1911, 



