OK THE LIFE-HISTOET OF CEETAIN ACAEIKA. 371 



The Sypopus Question, or the Life-History of certain Acarina. 

 By A. D. Michael, F.L.S., E.E.M.S. 



(Bead January 17, 1884.) 

 [Plate XV.] 



The Acarina are so little known in this country, that it is neces- 

 sary to commence by stating what a Sypopus is, and what are 

 the questions concerning it. 



In 1735 de Greer* noticed, for the first time, on the House- 

 fly {Musca domesticd) a tiny red mite, with an oval body enclosed 

 in a chitinous carapace ; and having, in lieu of any ordinary 

 mouth, a minute membranous tube, apparently closed, but fur- 

 nished with two setae. The two anterior pairs of legs were thick 

 and well-developed, but the fourth pair terminated in long setae 

 instead of any claw or sucker, resembling in this those of the 

 Itch-mite {Sarcoptes scaiiei). 



Linnseusf adopted the description of de Greer, and called the 

 creature Acarus muscartim. 



GeoffroyJ also found what may be presumed to be the same 

 thing; he called it "the brown fly-mite." 



Hermann§, in 1757, found upon the ventral surface and legs 

 of a Scarahceus larva and the larva of Osmoderma eremita, a 

 large number of small red-brown mites, with short legs and 

 spines to the tarsi ; these he called Acarus spinitarsus. His figure, 

 looked at by the light of our present, somewhat wider, knowledge, 

 leaves no doubt of the analogy between this and de Geer's 

 species. 



Schrank|| in 1781 gave a description of a small mite which he 

 found upon a male Gamasus (his Acarus crasstpes) , and which 

 he called Acarus acarorum. This, again, is evidently an allied 

 creature. 



Duges^ in 1834 found, on a Sister, a minute mite which he 

 regarded as being identical with Hermann's Acarus spinitarsus. 

 He created the genus Hypopus for it, and he included in the 

 same genus de Geer's Acarus muscarum and also Lyonnet's pou 



* De Geer, vol. viii. p. 115, pi. vii. figs. 1, 2, 3. 



t ' Systema Nature.' 



\ ' Histoire des Insectes,' t. ii. p. 624. no. 6. 



§ 'Memoire Apterologique ' (Strasbourg, 1804), p. 87, pi. vi. fig. 5. 



II ' Enumeratio insectorum Austrise ' (Augustse Vindelicorum), p. 524. 



^ Ann. Sci. Nat. 2^ ser. t. i. p. 37. 



