DESCRIPTIONS OF GENERA AND SPECIES. 251 



called G. Canestrinii in my cabinet long before, but 

 being busy with other families of Acarina I had not 

 published anything on the subject. In 1887 Armanelli 

 described G. Canestrinii as a new species, and in 1888 

 Canestrini adopted that specific name for that species, 

 and retained G. plumiger for the present one ; in which 

 he has been followed by Berlese and Kramer, so that 

 it disturbs nomenclature less to leave the names as 

 Canestrini used them than to treat what he called G. 

 Canestrinii as Koch's original G. plumiger, and to give 

 a new name to the present species. As Koch's figure 

 and description are uncertain I do not feel bound to do 

 so, although unfortunately Armanelli and Canestrini 

 fell into a grave error in describing G. Canestrinii; 

 this error would deceive any student. It was not until 

 1891 that Berlese examined Canestrini's specimens, 

 which Canestrini had from Armanelli, and discovered 

 the error in the description. The matter is rather 

 complicated by the fact that Canestrini in 1888 

 described as new a species which he called G. inter- 

 medius* and which he says is intermediate between 

 G. plumiger and G. spinipes. Berlese, in 1898,t says 

 that his own drawings of G. plumiger in 1884 above 

 referred to, were partly taken from G. plumiger and 

 partly from G. intermedius, and he specifies which 

 drawings were taken from each ; but Berlese, in the 

 very short note which he gives of the latter species, 

 seems to me to give it the characters which Canestrini 

 allotted to G. plumiger, and to transfer to that species 

 those which Canestrini gave for G. intermedius. 



Koch's original drawing and description of his 

 Acarus plumiger are very imperfect ; they might easily 

 refer either to the male of G. Canestrinii or the female 

 of the present species, or, possibly, even to G. inter- 

 medius ; they would not, I think, have been so appli- 

 cable to the female of r. Canestrinii or the male of 

 the present species. There are certain reasons to 



* I have found this species in the Tyrol, but not in England. 

 f 'A. M. S.,'fasc. xci. No. 10. 



