LIFE-HISTOBIES OF GAMASIN-E. 299 



rear throve at all well when supplied only with decaying vegeta- 

 tion ; and a comparison of their construction with that of other 

 families of Acarina led me irresistibly to the conclusion that they 

 were chiefly or entirely predatory. The remarkable power of 

 darting each mandible separately with speed and accuracy of aim 

 far in advance of the body, the powerful retractile muscles attached 

 to these mandibles, the organization of the remainder of the 

 mouth, the extreme swiftness of the creatures, the use of the 

 front legs as tactile organs only, and not for the purposes of 

 locomotion, and the ample supply of tactile hairs in front ouly all 

 seemed to me to fit the animals for a predatory life, and to indicate 

 habits similar to those of Gheyletus and Troiribidium rather than 

 of the true vegetable-feeders, such as the Oribatida3, Tetranachi 

 &c. In this I was confirmed by frequently capturing Gamasids 

 with small Thysanuridse firmly held in their mandibles, a circum- 

 stance surprising enough, as one would hardly have expected that 

 any development of the tactile sense would have enabled an eye- 

 less being such as Gamasus to capture such active insects as 

 Podura &c. ; they are, however, certainly able to do so. 



There are one or two remarks in the earlier writers which point 

 in the direction of predatory habits. Thus Duges*, speaking of 

 the so-called Gamasus coleoptratorum, says : — In winter they are 

 found under stones, and there doubtless live on other Acari ; at 

 all events, I have seen small Trombidies devoured by Gamasus 

 testudinarius. Gervais also f, speaking of an unidentified species, 

 says: — I have seen it seize a small Myriapod in its didactyle 

 mandibles and run off rapidly with it. Led by these considera- 

 tions, I determined to try feeding my Gamasids with cheese- 

 mites. I first placed a single Gamasid in a cell and shook in some 

 cheese-mites ; the success was quite unmistakable. The instant 

 that a cheese-mite touched one of the tactile hairs on the fore 

 legs of the Gamasus, it was seized in the mandibles of the latter, 

 drawn to the mouth, and sucked dry ; the same took place with 

 another and another, until the Gamasus was satiated. Since that 

 time I have fed my Gamasids entirely upon cheese-mites with 

 complete success ; but they have sometimes varied their diet by 

 eating one another. I am therefore of opinion that, at all events 



* "Eeckerches sur l'ordre des Acariens." Troisieine niernoire. Ann. des Sci. 

 Nat. 1834, t. ii. p. 26. 



t Walckenaer's ' Histoire naturelle des Insects, Apteres/t. iii. p. 215. 



