246 ARACHNOIDEA. 



CASE the preceding. One of these Hypopi was fixed on the back, and 

 the other on the abdominal face, in such a manner, that looking 

 at the Gamasus from its upper side, its parasites both appeared 

 as if in the abdomen, and we entertained for a moment the con- 

 viction that we had, under our eyes, the proof of the truth of the 

 assertion of Dujardin that our Gamasus was about to bring forth 

 a living larva with a Hypopial form. We know, says he, that 

 some Gamasidce, the Pteropti amongst others, bring forth living 

 octopod larv32. 



*' Opportunity having permitted us to meet several times Hypopi 

 attached to Gamasi, and to study them in all their phases, after 

 having also encountered the veritable larvae of Gamasi, always 

 similar to their parents, whether hexapod or octopod, we have 

 thus acquired the proof that we had been the plaything of an ilhtsion 

 and that the Hypopi are not the normal larvae of Gamasi as 

 Dujardin supposed." We have quoted this passage entire, and 

 in Megnin's own words, first to show the wide dispersion of the 

 Hypopi among insects, which, according to our view, is consistent 

 with its being a general parasite seeking whom it may devour, but 

 inconsistent with its being a phase of developement of a particular 

 insect; and, second, to show, by the words we have printed in 

 italics, that M. Megnin really did see a Hypopus inside of a 

 Gamasus, but disbelieved his eyes, and regarded himself as 

 the plaything of an illusion, not from any correction of his obser- 

 vation, but from abstract reasoning that it could not possibly be 

 correct. He reasoned himself out of his own senses. It looks as 

 if he had made up his mind that anything inside the Gamasus 

 could only be a phase of Gamasus ; and as from independent 

 observation he was sure that its larvae was different, he came to 

 the conclusion that what he saw was not there, but somewhere 

 else, and only appeared to be there by an optical illusion. 



This is not the only insect besides Tyroglyphus, that the 

 Hypopus has been found in. Mt. Tatem described and figured 

 (Monthly Micro. Journ., 1872) a Hypopus under the name of 



