STANDEN : OBSERVATIONS ON REPRODUCTION OF DART. 37 



May 2. — During past fortnight both snails have often been in 

 the burrow, sometimes remaining there a whole day. 

 They have fed greedily, and eaten remarkable quanti- 

 ties of chalk, but I find no eggs as yet. 



May II. — This morning find snails pairing as actively as ever. 

 In the evening find pair of darts on side of glass, and 

 snails showing usual symptoms. 



May 18. — Snails for several days been in and out of burrow 

 frequently, but am losing faith in their actions, having 

 been so often disappointed ! 



May 22. — Pairing going on as usual, and, later, find two more 

 darts detached. 



May JO. — Take out the dextral snail. 



June 2. — Find about a dozen very thin-shelled eggs in bottom 

 of burrow, but by which laid do not know, as I did not 

 examine when I removed dextral one. Eggs do not 

 look promising, but hope for some result at last. 



This was my last entry. No young resulted, and I had to 

 give up hopes of rearing a sinistral brood; the eggs speedily 

 shrivelled up, being evidently abortive. The dextral snail pro- 

 duced no eggs, and though I placed the snails together, after a 

 few weeks' isolation, they made no further attempt to pair. 



Early in October the sinistral snail showed signs of droop- 

 ing, its body becoming flaccid and much discoloured. I had 

 its photo, taken, whilst crawling on a piece of glass, by Mr. 

 Hoyle, and we then noticed that its body was full of some kind 

 of larvae, feeding — ichneumon-like — without touching a vital 

 part. The snail continued to take a little food until its death 

 about ten days later, and the larvae then came out and at once 

 pupated. They were curious woodlouse-like creatures, and 

 when the perfect insects emerged from the pupa they were 

 identified by Mr. J. Ray Hardy as one of the Diptera — Droso- 

 phila cellarius Linne, a generally-common little fly, often found 

 in cellars, feeding upon decayed bones, cloth, worms, grease, 



