88 Mr. A. ]\lurray on the Relatioiis 



speak to it from experience. In plaeing the nest from which 

 I took my Rhipiphori in the South-Kensing-ton IMiiseum, I 

 thought it might be desirable to mark the cells out of which I 

 had taken Bhip)ij)hori -^ and I accordingly set about doing so 

 by painting blue the lid of each cell out of which I took one. 

 At first I attem])ted to do it by first taking out the insect and 

 then painting the lid ; but 1 found the short sjiace of time 

 between laying down the forceps and taking up the painting- 

 brush sufficient to efface or render uncertain the identity of 

 the cell from which it had been taken. I therefore had to 

 take the precaution of painting the half-opened lid before I 

 drew out the RMpipliorus. 



But, further, if the rate and mode of growth of the Rhipi- 

 phori is that stated, they should always be found engaged in 

 the way Mr. Stone describes. They should always be found 

 in sealed cells, if one wasp-grub is sufficient to nourish them ; 

 whereas this is the only instance that has ever been observed 

 of it. (Mr. Smith says no ; but I shall presently show that it 

 is.) Mr. Stone himself records having found a number of 

 larv£e of Rhiinphorus which we may fairly infer were not so 

 occupied, for he would have recorded it had they been so : 

 two he mentions having found solitary in worker-cells ; and 

 although he does not specify where or how he found the others 

 engaged, still, if not in a cell with a wasp-grub, there is only 

 one other place for them to be found in, viz. solitary in cells 

 by themselves. Now I should like Mr. Smith to say what the 

 mass of the larva3 are doing in cells by themselves. If it had 

 been pupa^, we might have inferred that they had completed 

 their task, eaten up their man, and retired from active life : 

 but larvaj are different ; they have still more or less of their 

 task to do. Again, if Mr. Stone's observation is correct, we 

 should never see any half-grown larvae. There should be no 

 medium between a " minute " one and a full-grown one, ex- 

 cept during the forty-eight hours at which it is at its meal ; 

 but Mr. Smith speaks of specimens of under-grown larvae ; 

 and if I am to suppose that the grubs I saw with a curd-like 

 interior shining through the back were Rhipi2)Jiorus-gYiihs, 

 then I can say for myself that I saw them of all sizes. In 

 relation to this I may remark that Mr. Smith founds on the 

 size of the perfect insect an argument which I am sure, on re- 

 consideration, he will abandon. He argues that insects which 

 in their larval state are dependent for their sustenance on 

 chance or irregular supplies of food are apt to vary much in 

 size, which is quite true ; but he goes on to instance the Rhi- 

 piphorus as one of the examples of parasites that differ greatly 

 in size. Now this, although true to the letter, is not true in 



