Vol. 55, pp. 121-124 August 13. 1942 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WA$^&TON JitiGTON -fc—^ A< iri 9 1 ' O/i? SOME NOTES ON THE TAXONOMY OF GRAIN MITES. (ACARINA: AC ARID AE, FORMERLY TYROGLYPHIDAE). BY H. E. EWING and HERBERT H. S. NESBITT. The term "grain mites" has been applied either to some or all of the members of a group long known under the family name Tyroglyphidae. It is here used in the broader sense as applied to all members of that group. The name "cheese mites" also has been given to members of the same family, but is less appropriate when applied to the entire family, since the mites are not so frequently found in cheese as in grain. These acarids are medium sized, with a soft skin, and bear long and frequently beautifully modified setae. While most of the external structures may be adequately studied with lower magnifications of the compound microscope, the very fine barbs and other structures of these large, modified setae can be properly observed only in specially mounted specimens and with the aid of an oil-immersion lens. It is for this reason that nearly all the earlier descriptions of these mites are inadequate, and also the reason why the synonymy of the different species has become greatly involved. The notes here presented are the result of the joint studies of the two authors, made at the United States National Museum late in the year 1941. The material at hand was that contained in the National Museum, .plus a large collection of Canadian grain mites and some exchanges from abroad. The old types in the National Museum were found usually to have been mounted in balsam and were therefore in rather poor shape for study. Fortunately, however, usually several or even many cotypes of a single species were present, and structures which would have been missed on a single mount were finally fairly well appraised by a study of many speci-mens mounted in different positions. 26— Pboc. Biol. Soc. Wash., Vol. 55, 1942. (121)
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