146 BKIT1SH TYKOULYPHIM1. 



with the Hypopus of Tyroglyphus mycophagus, Megnin, 

 but I cannot see that either Hermann's figure or 

 description affords any possibility of identifying it with 

 this or any other species. 



Schrank * in 1781 gave a description of a small 

 mite which he found upon a male Gamasus (his 

 Acarus crassipes), and which he called Acarus aca- 

 rorum; this again is evidently a Hypopus. 



Duges in 1834 1 found upon a Sister a minute mite 

 which he regarded as being identical with Hermann's 

 Acarus spinitarsus. He created the genus Hypopus to 

 receive it, and he included de Geer's Acarus muscarum 

 and also Lyonnet's " pou de limacou " in the same 

 genus ; he noticed the singular supposed mouth or lip 

 with its two setas, but mistook the ventral suckers for 

 stigmata. In his abstract of the genera J he puts a ? 

 as to whether the creature is a larva; it is perhaps 

 singular that Duges should have done this in the very 

 paper in which he created the genus, but such is the 

 fact ; I believe that it is the first occasion on which 

 any hint was given by anyone that the Acarus in 

 question might be immature : all previous writers had 

 confidently described it as adult. Duges states that he 

 had only a single specimen. 



Dufour in 1839 added two supposed species to 

 Duges' genus ; one he found living in closely packed 

 groups on the head and thorax of Coleoptera of the 

 genus Feronia, and called Hypopus feroniarum ; the 

 other he found upon Diptera of the genus Sapromysa, 

 and called Hypopus sapromysarum. Dufour evidently 

 regarded them as adult creatures specially parasitic 

 upon the particular insect upon which he found them. 

 Megnin and Canestrini identify Dufour's H. feroni- 



* "Enumeratio insectoruin Austrise indigenoruui," 'Augustas Vin- 

 delicorum,' p. 524. 



j" " Recherches sur 1'ovdre des Acariens," 3me memoire in 'Ann. 

 Sci. Nat.,' 2 ser., t. ii, p. 37. 



J Op. cit., Ire memoire, ibid., t. i, p. 20. 



" Description et figures de quelques parasites de 1'ordre des 

 Acariens," in ' Ann. Sci. Nat.,' 2 ser., t. xi, p. 278. 



