5. 



50 (db. a. c. oudemans). new list of dutch acaui, li. 



The adults live tree and are well 



i chitinized 2. Laelaptinae. 



*• ' The adulls are parasites of Verte- 

 1 brates, and are less chitinized or 



! quite soft 5 



Mentum present 3. Dermanyssinae. 



Mentum absent 4. Spinturnicinae. 



Q^ Only one subfamily 5. Caelenopsinae. 



The <? genital aperture approaches 

 the anterior border of the sternal 



shield „ . . .6. Rhodacarinae. 



The c? genital aperture between the 



3d and 4th pair of coxae . .8 

 The Î genital aperture is a trans- 

 verse split between the steinal 



and genital shields 9 



The ? genital aperture is a large, 

 more or less oval hole in the 

 sternal shield, shut by an oval 



valvule 10 



The chelae in both sexes destitute 



of appendages 7. Epicriinae. 



The chelae in both sexes with ap- 

 pendages 8. Antennophorinae. 



10. Only one subfamily 9. Uropodinae. 



63, Rhodacarus roseus Oudms., nov. sp. 

 (With Plate 6, fig. 115—120). 



The name of this species already indicates which effect it made 

 on me, when I examined decaying leaves from a definite spot in 

 the Haarlemmer Hout. Its coìonr is the most brillant rose, the 

 lightest in the centre of Ihe animal, darker on the sides, whilst 

 the mandibles are of the purest carmine. 



The animal is perfectly transparent. It has no heart. 



