DEVELOPMENT AND IMMATURE STAGES. 147 



arum and also Claparede's H. Dugesii * with the 

 Hypopus of Histiostoma rostro-serratum ; in the case 

 of Claparede's form this is probably right, but in that 

 of Duf our's it must I think be considered doubtful. 

 Duiour in the same paper instituted a new genus, 

 Trichodactylu8 9 i for an apparently somewhat allied 

 Acarus which he found upon bees of the genus 

 Qsmia. 



C. L. Koch { in his great but faulty work admits 

 the genus Hi/popus 9 but gives only one species which 

 he found in numbers on Julius unilineatus, and calls 

 Hypopus julorum- ; it is curious that Koch says that he 

 frequently saw the c? and $ in copo. We know now 

 that there are not any males or females capable of 

 coition, all being immature ; what Koch doubtless saw 

 was two individuals adhering to each other by their 

 ventral suckers, as they will readily do to any polished 

 surface. In his later work Koch transfers A. spini- 

 tarsus, which he treats as one of his own species, A. 

 muscarum, and three other species, or supposed 

 species, to the genus ; none of these are really Hypopi 

 at all, but are probably all Uropoda, some adult, some 

 immature. Koch in the same work founded a new 

 genus Homopus for two somewhat similar creatures, 

 but with certain structural differences which will be 

 hereafter described ; these he called Horn opus sciurinus 

 and H. kypudsei after the animals he had found them 

 upon; || he had at first called the former species 

 De rmaleichus sciurinus. ,^[ 



Dujardin ** in 1843 found on the wing of a bee a 

 small mite for which he originated a new genus Anaetits, 



* " Studien an Acariden," 1868, in ' Z. wiss. Zool.,' Bd, xviii, p. 506, 

 T. xxxvii, fig. 6. 



f This name failed, being preoccupied by Latreille for a genus of 

 Crustacea in 1824. 



I Koch, D. C., 1844, Heft 38, fig. 20. 



Koch, 'Uebersi,' Heft 3, 1842, p. 129. 



|| Ibid., p. 120. 



f Koch, D. C., Heft 33, fig. 7. 



** ' Ann. Sci. Nat.,' 3e ser., Zool.,' t. ii, p. 245 ; ' L'Institut,' No. 454 

 p. 316. 



