1853.] Linnean Society. 247 



solution he founds on the mode of spawning described by Mr. Ellis 

 in his ' Natural History of the Salmon,' from which it would appear 

 that the male and female fishes having jointly made a furrow in the 

 gravel, place themselves one on each side of it, and throwing them- 

 selves on their sides " again come together, and rubbing against 

 each other, both shed their spawn into the furrow at the same time. 

 This process is not completed at once ; it requires from eight to 

 twelve days for them to lay all their spawn." Mr. Hogg argues 

 from this description, that it is possible that the female trout from 

 which Dr. Robertson took the ova might have gone through this 

 process with the male, and might have thus received the fecundating 

 influence, just before she was caught ; but on this solution he does 

 not rely. He thinks it more probable that in the running stream in 

 which the perforated zinc box was placed, there were some male 

 trouts which had deposited their milt near the box, and that some 

 of the milt might have been carried with the stream through the 

 holes of the box, and have so fecundated the ova within it. In con- 

 clusion, he suggested, that as doubts still exist as to the processes 

 which the male and female salmon and trouts naturally adopt at the 

 spawning season, experiments on the subject might readily be un- 

 dertaken, by confining them, at the proper seasons, in large glass 

 cases or tanks, covered over with a coarse wire gauze, such as those 

 which have recently been constructed in the Water-vivary of the 

 Zoological Gardens, as a name for which he suggests the word 

 Hydrozogrium, compounded of vlwp, aqua, and ^ujypelov, vivarium. 

 A stream of fresh water, regulated by pipes, could easily be supplied 

 in all districts where the Salmon- tribe abounds. 



Read also " Notes on the Dipterous parasites which attack the 

 common Earwig and the Emperor Moth." By George Newport, 

 Esq., F.R.S., F.L.S. &c. 



After remarking that it is well known to naturalists that many 

 Dipterous insects of the family Tachinarice infest the Lepidoptera, 

 Hymenoptera and Coleoptera, Mr. Newport stated that he has recently 

 found one of the Dermaptera, also the common Earwig, to be subject 

 to the attacks of a species of the same family. He has obtained this 

 parasite, both in its larva and pupa state, from earwigs collected in the 

 autumn in the neighbourhood of London. The earwig is attacked 

 during its larva, or in the earlier period of its pupa state, when the 

 covering of its body is soft and easily perforated. The fly then attaches 

 a single egg to some part of its surface, and the young parasite hatched 

 from this penetrates into the abdomen of its victim, and there con- 



