2 ARKIV FÖR ZOOLOGI. BÄND 7. NIO 12. 



Araongst a small collection of exotic acari, kindly sub- 

 mitted to me for Identification by Mr S. Hirst of the British 

 Museum, was another myriopodophilous mite, found onRhombo- 

 cephaliis gigantea, L. in Trinidad. The specimen was a female, 

 but on further investigations Mr Hirst found three more 

 specimens, all males. 



The species is related to Discozercon Berl., but in that 

 genus Berlese expressly states that there are three 

 anal shields, two lateral and a posterior one, whereas in 

 the present form there is only one, a difference which, in 

 connection with the presence of jugular shields and the en- 

 tirely different shape of Discozercon, makes it necessary to 

 institute a new genus, which I propose to name Discome- 

 gistus, on account of its great resemblance to Echinomegistiis 

 Berl. and Neomegistus Tgdh. 



Unfortunately I have been unable to examine Berlese's 

 specimens and, in consequence, I am not in a position to 

 draw a detailed comparison between the two genera, which 

 would have been very desirable, but must confine myself to 

 Berlese's short description, in which no mention is made of 

 the mouth parts of either sex, nor of the genital shield of 

 the male. 



Diagnosis. 



Body flat, träns versally oval, wider than long. 

 Dorsal shield surrounded all round by a marginal 

 shield, which, from the shoulders backwards, bears 

 a dense row of fusif orm brist les. No j ugular shields. 

 Anal shield large, free, but contiguous to ventral 

 shield. ^ genital aperture between coxselll, J^ ster- 

 nal shield not fused with ventral shield. ^ genital 

 shield fused with ventral shield; genital aperture 

 on a level with the middle of coxse III. Metapodial 

 shields large, modified into thin-walled blotches, 

 surrounded by a high ridge. Stigmata small ; peritre- 

 mata running forward to coxte I. Mandibles almost 

 edentate, with solid flagellum and well developed 

 lanceolate appendage; maxillary lobes with large, 

 thin median blades. Legs I with telotarsus and 

 ambulacres; ambulacres without or with rudimen- 

 tary claws. 



