DESCRIPTIONS OF GENERA AND SPECIES. 209 



fasc. xxix, No. 4, Berlese does not draw any tubercles 

 on the back or the margin. For this and other reasons 

 they would not appear to be identical ; but in the 

 illustrations of this species accompanying the descrip- 

 tion of the genus, fasc. Ixxix, No. G, the tubercles are 

 drawn, and the whole creature is much more like 

 Megnin's, but Berlese identifies his two drawings as 

 being the same creature. Berlese himself appears to 

 have had considerable doubt upon the subject. In the 

 paper by Gr. Canestrini and Berlese jointly, called 

 " Nuovi Acari," * the authors say that Tyroglyptwa 

 rostro-serratus, Megnin, and Hisliostoma pectineum, 

 Kramer, are the same creature ; but later in the same 

 year Berlese t corrects this, and says that they are 

 different. This is confirmed by Canestrini, who iden- 

 tifies Histiostoma pectineum, Kramer, with Hypopus 

 juliorum, Koch. Berlese follows this in 1886 (as 

 shown in the synonymy), but in his " Ordo Crypto- 

 stigmata," forming the summary of the same work, in 

 1897, he again identifies Hypopus julorum and Phyllo- 

 stoma pectineum with Tyroglyphus rostro-serratus, and 

 calls the species Histiostoma rostro-serratum. 



Female. Male. 



Length . . . . '38 to '60 mm. '25 to '45 mm. 



Typical length (English specimens) '55 mm. '40 mm. 



breadth . . . '30 -20 



length of legs, first and 



fourth pairs . . '20 -17 



length of legs, second and 



third pairs . . '15 *14 



This was the first species of the genus discovered, 

 and must be considered the type species. 



Colour. Light dirty yellowish, or buff ; frequently, 

 perhaps usually, showing a good deal of opaque white 

 or yellowish white on the dorsal surface. This arises 

 from accumulations of white excremental matter show- 

 ing through the dorsal cuticle. Legs very light yel- 

 lowish red. 



* In ' Atti Soc. Veneto -Trent,' 1881, vol. viii. 

 t ' Indagini,' etc., 1. c., p. 150. 



