On the new genus Ceratoacacus Ewing 
(Acarina). 
By 
Ivar Trägårdh. 
When reading the description of this new genus pub- 
lished by EWING in »fournal of entomology and zoology», 
vol. 5. n:0 3,1913 one gets the impression that the american 
acaridologists must have great difficulty in getting access 
even to widely spread European literature on mites. 
Any specialist on the group in Europe, who is even 
moderately familiar with the literature, will at once perceive, 
that the »new» genus is nothing else than a Ladzdostoma, 
wherefore it is quite inappropriate to place it in the Ceculde. 
The genus Zabrdostoma was created by P. KRAMER in 
1879 (Arch. f. Nature. 45 arg. 1 Bd, p. 13—16, fig. 1 a—i, 
tavl. II); the following year A. D. MICHAEL in England found 
it and gave an excellent description of it accompanied by a 
plate, containing beautiful drawings both of the adult and 
the nymph (Journ. Quekett Micr. Club, vol. 6, n:o 44, 1880 
p. 107—113, pl. 6). 
Shortly afterwards G. and R. CANESTRINI' proved that 
the genus was identical with the genus Nzcoletra which name 
was changed by them in Nzcoletiella, since the former was 
preoccupied in another group, the 7hysanura. This latter 
name is, however, not valid, but the genus has to be called 
Labidostoma. 
1 Atti di R. Istituto Veneto di Scienze etc. Ser. 5, 1881—1882 p. 
927. pl'#r0): 
