10 BRITISH TYROGLYPHIDJE. 



species have become of special interest as having given 

 rise to new genera, or otherwise. 



The work of Duges,* which was practically the 

 commencement of the modern classification of Acarina, 

 was a general classificatory paper, and has from that 

 point of view already been dealt with at page 35 of my 

 ' British Oribatidas,' published by the Ray Society ; as 

 this is a continuation of the same series, I do not pro- 

 pose to repeat what I there said, but Duges also de- 

 votes a short space to remarks upon each family. The 

 TyroglyphidaB occupy only four pages. He includes 

 them and the Sarcoptidge, in the restricted sense of that 

 word (used as not including the Tyroglyphidas), in one 

 family under the name of Acares, which he defines as 

 Acari with caronculated feet, chelate mandibles, and 

 palpi very difficult to see and adherent to the lip. He 

 makes two genera only of Tyroglyphidge, viz. (1) Hypo- 

 pus, which is now known to be only a stage in the life- 

 history, not a genus of adults ; t and (2) Acarus, which 

 therefore practically includes the whole of the Tyrogly- 

 phidae. He does not describe any new species, only 

 mentioning a few already described by de deer, Her- 

 mann, and Lyonet; he, however, describes from per- 

 sonal observation what he considers to be the Acrn* 

 domesticus of de Greer, but it is very doubtful whether 

 he really had that species under observation. He 

 makes it the type of the genus (which equalled the 

 family), perhaps overlooking the fact that a different 

 type already existed. There are a few figures and a 

 short description of the external anatomy ; which how- 

 ever are not quite reliable, and there are a few obser- 

 vations on habits. 



C. L. Koch was the next author whose works need 

 be mentioned. His two works, J commenced in 1835, 



* " Recherches sur 1'ordre des Acariens," Troisiemc memoire, in 

 ' Ann. Sci. Nat.,' ser. 2, t. ii (1834), pp. 3742. 



f See this book, Chapter VI, on Development and the Immature 

 Stages. 



J " Deutschlands Crustaceen Miriapoden und Arachniden, ein 



