520 IVAR TRÀGÀRDH 



INTRODUCTORY NOTES 



If it be true that the exploration of the fauna of the caves 

 has only just begun, and. that for the time being we only know 

 an infinitely small portion of the inhabitants of the caves, this 

 holds good in a still higher degree with regard to the acari. 



As a mat ter of fact, we do not even know for certain whether 

 there are any troglophilous or troglobious acari or not, still 

 less, whether the cavernicolous forms differ in any respects from 

 the non-cavernicolous. 



It is true, that several acari hâve been recorded from the 

 caves, both in Europe and America, but, unfortunately, they 

 hâve not been described by specialists, and it would, in consé- 

 quence, be necessary to examine the type spécimens in order 

 to obtain an accurate idea of their systematic position. 



As Hamann, in 1896, published a list of the cavernicolous 

 acari, it is not necessary to do so hère. His list contains 18 

 species, including also parasitic forms from Chiroptera. Of 

 thèse I hâve been able to identify one with a probability, 

 amounting almost to a certainty, viz. Gamasus niveus Wank., 

 and with less certainty an other, viz, Scyphius spelaeus 

 Wank. 



In his treatise on the biospéological problems, in 1907 

 (p. 445), Racovitza sums up our knowledge of the acari as 

 follows : « Les Lucifuges et les Saprophages se rencontrent fré- 

 quemment dans les cavernes ; mais ces Animaux ont été trop 

 peu étudiés encore pour qu'on puisse seulement savoir s'il y 

 a des formes exclusivement cavernicoles. On trouve des formes 

 décolorées, aveugles, à très longues pattes, mais on peut en 

 rencontrer de semblables sous les pierres et aussi dans la 

 terre. » 



This being tlie case, it gave me great pleasure to be able to 

 accept Racovitza's gênerons ofïer to let me study the fine coUec- 



