INTRODUCTORY. 7 



bably the great Swedish author included many species 

 under the one title. T. siro and T. loncfior are not 

 usually regarded as particularly handsome or attractive 

 species, nor are they entitled to be, although the latter 

 is not without its beauty if prejudice be excluded ; but 

 such species as Glycyphagus Canestrinii, G-. plumiger, (T. 

 palmifer, and many others, are amongst the most beauti- 

 ful of Acari, and it is a very great mistake to imagine 

 that Acari are not ever beautiful. A female Glycy- 

 phtiyus Canestrinii, well seen with dark-ground illumi- 

 nation and a sufficient amplification ; its whole body 

 surrounded by its peripheral row of great ostrich 

 plume-like hairs, all shining like frosted silver, is 

 a sight which will not readily be forgotten by any one 

 possessed of any appreciation of beauty. 



The popular name of " cheese-mites " is generally 

 applied to the whole family ; but is only really applic- 

 able to quite a few species, and even these are mostly 

 found quite as often on other substances as on cheese. 



The Tyroglyphidse, like the Sarcoptidae and Oriba- 

 tidas, have legs of five free joints ; but unlike those 

 families the tarsus is always terminated by a single 

 claw, varying greatly in size in different species, either 

 with or without a caroncle. 



It may be mentioned that the Tyroglyphidse, being 

 minute creatures, mostly either white or without con- 

 spicuous colouring, and some of them being very active 

 and constantly moving about and getting into un- 

 expected places with great rapidity, and being carried 

 by wind, water, and other agencies, are apt to be 

 described by persons not well acquainted with this 

 character of the family, and of some other groups $f 

 Acarina, as coming from places and in modes which are 

 not correct, although supposed to be so. Thus Mr. 

 Cross believed that he had created one species in his 

 galvanic batteries, and Turpin and others agreed with 

 him ; not knowing that the species swarmed in houses 

 generally : they have been described as brought up 

 living from the depths of the sea, when in reality the 



