No. XX.— THE ACARINA OF THE SEYCHELLES. 



By Cecil Warburton, M.A. 



(Plates 17 — 19, and 4 Text-figures.) 



(Communicated by Prof. J. Stanley Gardiner, M.A., F.L.S.) 



Read 20 June, 1912. 



The Acarina here recorded were obtained from two sources. A certain number — 

 naturally comprising the larger forms for the most part — were collected on the spot and 

 were submitted for examination either mounted on cards, or in tubes containing alcohol. 

 It was not to be expected that such minute objects as the smaller Oribatidse should be 

 represented in such a collection, and the presence of numerous examples, considerably less 

 than a millimeter in length, was a matter of surprise. Few species, however, were 

 obtained in this way, the great bulk of the collection consisting of two large Oribatidse — 

 Oribata alata and Neoleodes rugosus, n. sp. — and some tubes of the huge Gamasoid mites 

 Holothyridse. 



The second source possesses a particular interest. Instead of troubling to collect 

 creatures so microscopic, membei's of the Expedition were asked to send home tins 

 containing fresh damp moss, in which many of the Oribatidaj habitually live. It had 

 been previously ascertained* that mites will arrive alive and in good condition in such 

 moss when despatched from the most distant parts of the world, even if the tins are 

 hermetically sealed. Obviously it is possible in the laboratory to detect objects which 

 would certainly be overlooked in the o23en, and any great extension of our knowledge of 

 Oribatida3 will probably come from the application of this method. Only once previously 

 has a record of mites obtained in this manner from a foreign country been published. In 

 1906 my friend Mr N. D. F. Pearce described, in the Journal of the Royal Microscopical 

 Society, the mites contained in moss from the Sikkim Himalaya. 



A simple machine devised by Berlese and described by him in " Redia," vol. i. p. 85, 

 is of the greatest assistance in collecting living mites from the moss or other material in 

 which they live. It consists essentially of a large tin funnel surrounded by a water-jacket. 

 The moss is placed on a tray of wire gauze at the top of the funnel, and the water 

 surrounding the funnel is heated by a Bunsen's burner. As the moss dries the mites 

 descend, till at length they drop down the funnel into a small vessel containing water, 

 placed ready for their reception. By this means the moss is searched much more 

 thoroughly and witli much less labour than by the alternative method of shirking it over 

 white paper and collecting the mites individually as they reveal themselves by commencing 

 to crawl about over the surface. 



* Proc. Cainli. Phil. Soc, vol. xiv., pt. 1, p. 1.3. 



