OR LIFE-HISTOET OP CBRTAIlSr ACAEIKA. 377 



Finally, in 1881, A. Berlese published a paper* in which he 

 in the main agreed with Megnin, but went somewhat further, 

 asserting that Kramer's Pygmepliorus was not an adult form, that 

 Hypopus took no nourishment, and was entirely without buccal 

 or anal apertures, that its labium was a tactile organ, and that all 

 Acarina which had rudimentary mouth-organs, and were with- 

 out buccal and anal openings, were hypopial forms. This paper 

 is complicated by the author's exceptional views as to poly- 

 morphism, &c. 



These are the principal records ; but Mr, J. S. Macintyre in- 

 formed me that he also has seen Tyroglyphi turn into Hypopi, 

 although I am not aware that he has published his observations. 



I have not attempted an exhaustive abstract of any of the 

 above-named papers, many of which are lengthy, but have simply 

 sought to set out, in as few words as possible, such parts as are 

 essential to an understanding o£ the aim and results of my own 

 observations ; and also, to some extent, to draw attention to 

 what has been done by others. To summarize the literature, 

 eight different suggestions are before the public as to what a 

 Hypopus really is ; these are made by the writers whose names 

 are set opposite to the respective explanations, viz. : — 



f Writers before 

 I Duges ; also 



1. JT2/|30|9MS is a separate family of adult ^carm« ...<( Koch,Dufour, 



I and some pre- 

 L sent authors. 



2. Hypopus is an immature stage of Gamasus .... Dujardin. 



3. Hypopus is an itch-mite Gerlach. 



4. Hypopus is the adult of both sexes of some I r* . • 

 species oi lyrogiyplius j 



5. Hypopus is the male of TyroglyjjJms . Claparede. 



6. Hypopus is the " cuirassed heteromorphous adven- \ 



titious nymph of Tyroglyphus," &c., appearing only ( Megnin^ Berlese, 

 for the distribution and preservation of the species f &c. 

 under adverse circumstances ) 



7. Hypopus is a ferocious parasite, sometimes ex- j 



ternal, sometimes internal, which ends by entirely (. * j . m ■ • 

 devouring its host from within, leaving only the T " ^' 



skin ) 



8. Hypopial form is a travelling dress Haller. 



It is the correctness or error of these diverse opinions that I 



* " Indagiui suUe Metamorfosi di alcuni acari insetticoli," Atti R. Ist. 

 Veneto di sci., lett. ed arti, ser. 5, vol. viii. 



