(db. a. c. oudemans) list of dutch acari. 247 



« Hydrachiidae Koch » , though Koch has never used this term 

 (Vega Exp. Vet. Arb. III. p. 525, 1881). Koch used the German 

 word « Wassermilben » , Ueb. Ar. Syst. III. p. 7. 1842. 



This group is divided into three smaller groups , viz. those of the 

 Hydrachnides Koch, 1842, Ejjlaldes Leach, \%\^djv^lIy(jrobaüdes 

 Koch 1842. 



4. The Uydrachiides of Koch 1842 (Ueb. Ar. Syst. III. p. 2G) 

 and Lebert 1874 (Bull. Soc. Vaud. Sc. Nat. XIII. p. 91.) are 

 called Hydrachnidae by Grube, 1859 (Arch. Nat. Liv-, Ehst-. 

 Kurl. (2) I. p. 434, 466), Megnin 1876, 1877, 1880, Kramer, 

 1877,1878, Haller, 1880, Canestrini, 1881, etc. 



Hydrarachnidae by Donnadieu in 1875 (Rech. Tétran. p. 9. and 

 Hydrachninae by Glaus in 1880 (Grundz. Zool. I. p. 653.) 



5. The group of the Eylaides Leach 1815 (Trans. Linn. Soc.) 

 is called Eylaidae by Kramer in 1877 (Arch. f. Nat. p. 241, 247 

 and Eylainae by Glaus in 1880 (Gi'undz. Zool. I. p. 653.) 



6. The group of the liygrohatides of Koch 1842. (Ueb. d. 

 Ar. Syst. III. p. 7) is called 



Hygrolatidae by Grube, 1859 (Arch. Nat. Liv-. Ehst-. Kurl. (2) 

 I. p. 434, 466), by Lebert, 1874 (Bull. Soc. Vaud. Sc. Nat. 

 XIII. p. 91), Kramer, Hauler, Megnin, etc. 



Atacidés by Donnadieu, 1875 (Rech. s. 1. Tétran. p. 9) and 

 by Megnin in 1876. (Journ. Anat. Phys. XII p. 293) and 1877 

 (Rev. Mag. Zool. p. 43) and 



Hygrohatiuae by Glaus, 1880, Grundz. Zool. I. p. 653. 



7. The name of Bradyhates wliich Neuman (Forh. Nat. Mod. 

 Kjöb. p. 409, 1873) gave to a genus with Bradyhates trmicatus 

 Neum. as type, must be changed into another, as this name is 

 already used in 1838 by Tschudi for Beptilia, and in 1846 by 

 Gray for Aves. 



8. Atax Fabr. 1805 is only a synonym to Uydrachia Müll. 

 1769, as it contains all the species of Müller. Atax Duces, non 

 Fabr., however, having liydracJina Jdstrionica Herrn, as type, is 

 well defined by Duces. 



He says (Ann. Sc. Nat. (2) I p. 17): 



