384 MR. A. D. MICHAEL ON HTPOPI, 



the claw of PedicuUts capitis. Tlie second and third legs are also 

 terminated by single claws, but less remarkable ia size and form. 

 Donnadieu says that Dufour has confounded the two species, and 

 that, probably from the imperfection of his instruments, he has 

 misdescribed tlie creatures in many respects, and in particular as 

 to the legs, where, in addition to other errors, he has described 

 double claws instead of single. Donnadieu's Acarids had a soft 

 closely- wrinkled skin resembling 8ar copies, to which genus h.e con- 

 siders Trichodactylus to be allied, although it is not subcutaneous. 

 Donnadieu describes both sexes, and gives details of the repro- 

 ductive organs and of the mode of copulation : he describes the 

 maxillse, mandibles, lingua, &c., and gives excellent drawings of 

 the whole. 



Dujardin considered that Dufour's Tricliodactylus was the same 

 as lEypopios, and, in spite of Donnadieu's details, Megnin, Ber- 

 lese, and others have maintained that the two so-called genera 

 are identical, and that consequently Trichodactylus consists of 

 immature forms, and not of species at all. I am not inclined to 

 offer an opinion as to what Dufour's species is upon the evidence 

 of his paper alone ; but I am indebted to the kindness of Prof. 

 Donnadieu for the loan of the only two specimens of his two species 

 which he still possesses, and the examination of them has decidedly 

 led me to the conclusion that they are not Hypopi, but are adult 

 crea.tures, and that, as far as I can judge, Donnadieu is right in 

 considering them to be somewhat allied to Sarcoptes. Whether 

 they be identical with Dufour's species seems to me a more 

 doubtful question. I may mention that Donnadieu's species are 

 very much larger than any Sypopi which I have ever seen. I 

 did not receive them or come to the conclusion that they were 

 good species, until after I had had the advantage of making the 

 investigations referred to below upon Mr. George's bee-para- 

 sites. 



In April 1879, Mr. C. F. George, of Kirton Lindsey, published 

 a short account of an Acarid which he found the previous year para- 

 sitic upon the Gamasidse which were infesting the Queen humble- 

 bees, particularly Bombus virginalis^ ; he says he " supposes it 

 must be a Sypopus (whatever that may be)." The whole of the 

 cephalothorax of this creature, which is far the largest portion of 

 it, is covered by a polished, chitinous carapace, extending greatly 



* " On the Mite of the Humble-Bee, Gamasus," Science Gossip, vol. xv. 

 pp. 81, 82 (1879). 



