350 PERCY SLADEN TRUST EXPEDITION 



There are special difficulties in dealing with specimens of the minute size of many of 

 the Oribatidae mites. They are frequently so small that it is impracticable to preserve 

 them separately in tubes of spirit, for, apart from the fact that their legs curl up so as to 

 obscure important points of structure, they are extremely liable to be lost altogether. It 

 is therefore generally necessary to mount them speedily in balsam, but even so many 

 characteristics easily visible in the living specimen are lost to sight. The ideal method 

 would be to examine each specimen and make elaborate notes upon it before mounting, 

 but this would presuppose an amount of leisure on the part of the investigator which is 

 very unlikely to be at his disposal. The consequence is that many specimens are secured 

 which may easily be new species, but of which a sufficiently clear view cannot be obtained 

 to make out the essential points, and it is only safe to describe such species as can be 

 examined with some degree of accuracy. 



(J)ribatid^, 



As far as investigation has at present proceeded there appears to be a remarkable 

 similarity between the Oribatid fauna of the most widely separated regions of the world. 

 No creatures would seem to be less likely to distribute themselves widely, since they are 

 wingless and destitute of the silken threads by which spiders migrate, nor do they infest 

 ships, or cling to animals or birds. Yet what appear to be jjrecisely the same forms occur 

 thousands of miles apart, and those which are obviously different seldom vary greatly from 

 the general European type. 



In the moss from the Sikkim Himalaya, Mr Pearce found 20 species, divided among 

 12 genera, and of these 12 were British. In the more plentiful material from the 

 Seychelles, omitting numerous unsatisfactory specimens, 36 species were made out, 

 representing 12 genera, and of these species 12 were British or at all events deserving of 

 no more than varietal rank. It is remarkable that four of the British species — Orihata 

 alata, Tegeocranus velatus, Hermannia convexa, and Nothrus tectorum were the same in 

 each case. No representatives of the genera Pelops or Cepheus were found. 



The following is a complete list of the Oribatidae from the Seychelles. 



OribatinSB. 15- NoUispis davipectinata var. calva, n. var. 



Oribaia alata (Herm.). 16- NotasjAs impolita, n. sp. 



Oribata cuspidata, Mich. 17. Notaspis reticulata, n. sp. 



Oribata brevis, n. sp. 18- Notaspis lamellicornis, n. sp. 



Oribata elongata, u. sp. 19- Notaspis flagellata, u. sp. 



Oribata mammillata, n. sp. 20. Notaspis simplex, n. sp. 



Oribata longissima, n. sp. 21. Notaspis acutipes, n. sp. 



Oribata seychdlensis, n. sp. 22. Notaspis frontata, n. sp. 



Oribata lata, n. sp. Damffiinae. 



Ttr i -J- 23. Amerus seychellensis, u. sp. 



NotaspidinsB. . T^ . . ^ 



24. Damoius rettarius, n. sp. 



9. TegeocroMus velatus, Mich. 55 Damoius complanatus, n. sp. 



10. Carabodes labyrinthicus, var. clavatus, n. var. 



11. Liacarus piriformis, n. sp. .NOtlirinSB. 



12. Notaspis splendens (C. L. Koch). 26. Hermannia convexa (C. L. Koch). 



13. Notaspis sculptilis, Warburton and Pearce. 27. Hermannia nasata, n. sp. 



14. Notaspis davipectinata, Mich. 28. Neoleodes rugosus, n. sp. 



