302 ME. A. D. MICHAEL ON THE 



which Gamasus crassipes is one ; and he abandons the division of 

 the dorsal plate as a means of classification. 



In 1879 * Kramer replied, and affirmed that some of the adult 

 Gamasinse do show divisions between the dorsal plates, and ad- 

 hered to it as a mode of distinction ; he states that he has seen 

 ripe eggs inside a species which he calls G. nemorensis, and which 

 had divided plates on the back. 



Linnaeus t also named another well-known species, his Acarus 

 (now Gamasus) crassipes. There has been a good deal of confu- 

 sion with this species — Schrank and others having called allied 

 species crassipes simply because they had the second pair of legs 

 thickened, which is certainly only characteristic of the males, and 

 is common to several species. Hermann, however, although his 

 description is imperfect, gives figures J which sufficiently identify 

 the Linnean species. Hermann also gives a similar species, but 

 without the thickened legs, which he calls Acarus testudinarius ; 

 and another, A. marginatus, the characteristic of which is showing 

 a soft white line between the single chitinous dorsal plate and 

 the ventral plate. 



Megnin asserts § : — First that the Gamasus crassipes of Duges 

 is the adult male of one of the three species of which coleoptra- 

 torum is the nymph ; but as Duges does not describe or figure 

 the species, but simply refers to Hermann, this is equivalent to 

 saying that coleoptratorum is the nymph of Hermann's crassipes. 

 Secondly, that testudinarius is the female of crassipes ; in this he 

 is followed by Canestrini and Fanzago||. And, thirdly, that the 

 characteristic of marginatus is simply that of the females of a 

 large portion of the genus. 



It was to assist in settling these various points and to learn 

 what else I could of the life-histories of these creatures that I 

 undertook the following observations, chiefly on crassipes and 

 coleoptratorum. Whatever may be their value, they are, to the 

 best of my ability, in every instance, faithful records of what I 

 have actually seen take place with selected and known specimens 

 in cages which I could place upon the stage of my microscope for 

 frequent watching. 



* " Ueber einige Unterschiede erwachsener und junger Gamasiden," Archiv 

 fur Naturgeschichte, 1879. 



t Syst. Nat. ed. 12, sp. 8 ; Faun. Suec. 1769. 



t Loc. tit. pi. 3. fig. 6, and pi. 9. Q, E. § Loc. cit. p. 330. 



|| " Intorno agli acari italiani," Atti del. E. 1st. Venet. di Sci. 1877-78. 



