Acari. 425 



As to Bdella littoralis it is a strictly littoral form which or the 

 eggs of which are apt to be dispersed by means of driftwood etc. 



Podothrombium bicolor var. ciirtipaipe, on the other hand, is more 

 particular; contrary to Bdella, the larvæ of which are free-living like 

 the adults, its larva is ectoparasitic and dependent on other arth- 

 ropods (spiders or insects); its geographical distribution consequently 

 becomes restricted to the places where suitable hosts occur. This 

 is, as pointed out by the author (13. p. 573), the most probable ex- 

 planation of the fact that no Trombidiidœ or Erythrœinœ , the larvæ 

 of which are all ectoparasitic, have been found on small, isolated 

 islands, as for instance Bear Island and Jan Mayen or in the regio 

 alpina superior of the mountains of arctic Lappland. 



Comparison with the fauna of the neighbourhood 

 of Scoresby Sound. 



As above mentioned the only other place on the East-coast of 

 Greenland at which the acarid fauna has been explored is Scoresby 

 Sound. From this place the following 14 species have been recorded: 



Oribatidœ: Oribata nolata Thor., Tectocepheus velatus Mich., 

 Nothrus horridiis Herm. var. borealis (Thor), Notaspis exilis Nie. var. 

 crassipes (L. Koch). Hermannia reticulata Thor. 



Trombidiidœ: Pentbaleus insiilamis Thor., P. hœmatopus Can., 

 Bdella littoralis (L.), Bryobia prcetiosa K., Podothrombium bicolor 

 (Herm.) var. curtipalpe Sig Thor, Erythrœus phalangioides (D.G.) var. 

 gracilipes (Kram.), Rhyncholophus miniatus (Herm.). 



Parasitidee: Eulœlaps ambulans Thor, Parasitus fucorum (D.O.). 



BIBLIOGRAPHY. 



1. Berlese, a. Acari nuovi , Manipulus secundus. — Redia, vol. 1 fasc. 2. — Flo- 



renz 1903. 



2. — - Acari nuovi, Manipulus 5 — 6. — Ibidem. Vol.6, fasc. 2. 1910. 



3. — - Lista di nuove specie e di nuovi generi di acari. — Ibidem. Vol. 6 , 



fasc. 2. 1910. 



4. — - Brevi diagnosi di generi e specie nuovi di acari. — Ibidem. V^ol. 



fasc. 2. 1910. 



5. .loHANSEN, F. Freshwater life in north-east Greenland. — Danraark-e.xpeditionen 



til Grönlands nordostkyst 1906—1908. — Bind 5. Nr. 6. (Særtryk 

 af "Meddelelser om Grønland" 45) — Kobenhavn 1911. 



