1891.] ASSOCIATION OF GAMASIDS WITH ANTS. 639 



considered joint work ; the observations and experiments were solely 

 my own, and I alone am responsible for any opinions expressed in 

 this memoir. 



For the identification of the species of Ants I am indebted to the 

 kindness of Mr. Edward Saunders. 



The Gamasidte are a family of tlie Acarina ; Megnin^ considers 

 them to be the most highly organized in the order and the nearest to 

 the Insecta ; in spite of the absence of eyes, which are fomidin some 

 other families, the great development of the brain and nervous 

 system, and the specialization of the trophi and the alimentary and 

 muscular organs, probably entitle them to this position. 



The family may be divided into four well-marked subfamilies, 

 viz. the PteroptincB, the Dermanyssince, the Uropodince, and the 

 Gamasince — the last-named being far the largest. The Pteroptince 

 are all parasites of Bats, the DermanyssincE of Birds or Bats ; these 

 two subfamilies may be wholly omitted from consideration for the 

 purposes of this paper ; it is amongst the Uropodince and GamasincB 

 alone that the facts here recorded arise. Both these families are 

 composed of creatures which in tiieir immature stages are soft and 

 white, but in their mature condition aie fully chitinized. In the 

 former group the chitin is very dense and hard, in the latter much 

 thinner and tougher ; the former are mostly rather slow and inactive, 

 the latter usually extremely quick and active. It used to be con- 

 sidered that the Gamasince lived wholly on vegetable matter in a 

 decaying condition ; in the year 1880, liowever, when I was trying 

 to rear a few of the species in confinement for the purpose of tracing 

 their life-histories, I entirely failed in getting them to live upon 

 vegetable matter, and thinking from the structure of their mouth- 

 organs that they must be predatory, I tried them with a diet of 

 living cheese-mites, upon which they throve admirably^ I have since 

 usually fed them in this manner, or at all events with small Acari or 

 Insects. Col. Blathwayt also, who has made numerous experiments 

 upon rearing them, has adopted my mode of feeding, apparently with 

 complete success, he also having failed with a vegetable diet ^. It is 

 evident therefore that some species of Gamasince, probably not all, 

 are predatory. As to the food of the Uropodince, I do not think 

 that we have any reliable information as yet : their extremely long 

 and slender mandibles with minute chelae seem as though intended 

 for introduction into very narrow passages ; their slowness hardly 

 seems fitted for a predatory life, as ihey certainly do not construct 

 any snare, and I have entirely i'ailed to rear them, and so I believe 

 has Col. Blathwayt*. 



^ " Memoire sur 1' organisation et la distribution zoologique des Acariens de la 

 famille des Gamasides." ' Eobin's Journ. de I'anat. et de la physiol.,' May 1876, 

 pp. 298-9. 



- " Observations on the Life-liistories of G-amasinffi," Joum. Linn. Soc, Zool. 

 vol. XV. (1881) p. 298. 



^ " On some common Species of Gamasidaa," Joarji. of Microsc. and Nat. Sci. 

 n. ser. vol. ii. 1889, p. 102. - ■:^.:X 



^ It is easy to rear the creatures in large jars' can baJiiing quantities of mate- 

 rial, but then they are useless for observation. ■ 



Proc. Zool. Soc— 1891, No. XLIfl. 43 



