240 BRITISH TYROGLYPHID^E. 



is the species really referred to by numerous French 

 writers on micrography, etc., when they speak of 

 Tyrogyphus farinas. 



It seems to me quite uncertain what the Acarus 

 domesticus of Latreille was.* 



Fumouze and Robin considered Lyonet's " troisieme 

 espece de mite" to be G. domesticus, lout, as before stated, 

 I think this very uncertain. 



Linnaeus does not mention domesticus in any edition 

 of the , ' Sy sterna Naturae ' published in his lifetime; 

 de G-eer remarks that Linnaeus did not distinguish 

 between this species and A. siro : after the death of 

 Linnaeus, and after the publication of de Geer's work, 

 Gmellin introduced A. domesticus into his edition of 

 the < Syst. Nat.' 



There can be but little doubt that by many ancient 

 and even some modern writers the specific name 

 domesticus has been used in error when the creature 

 really spoken of was T. siro, T. longior, or G. spinipes. 



This creature probably was the Acarus horridus of 

 Turpin,f which Mr. Cross thought that he had created 

 by electricity ; but it is not possible to be certain from 

 Turpin's paper. 



Female. Male. 



Length . . . '43 mm. to '55 mm. '36 mm. to '50 mm. 



Typical length about . *5 '48 



breadth about . '27 '25 



length of legs, first 



and second pairs . . "30 *27 



Typical length of tarsus of 



first pair . . . '13 '12 



Typical length of legs, third 



pair . . -35 '35 



Typical length of legs, 



fourth pair . . '37 '37 



Typical length of tarsus, 



fourth pair . . '18 '18 



This is one of the commonest of species ; it is found 

 in great quantities, chiefly in houses and buildings, 



* ' Genera Crustaceorum et Insectorum,' Paris, 1806-9, vol. i, pp. 

 150, 151 ; ' Hist. Nat. des Crustaces et des Insectes,' Paris, 1798, p. 400, 

 pi. Ixvi. 



t ' C. R. Ac. Sci.,' 1837, t. v, p. 672. 



