46 ACARIDEA. 
After having studied more attentively the European A. baccarum, L. (=cornigerum, 
Herm.), I believe that the above-named Guatemalan forms are but varieties of 
colour and age of this species, as I cannot find any tangible differences between my 
original drawings and European specimens, except those of size and colour, which in 
Actineda are of no value. ‘This view is confirmed by the circumstance that Berlese 
has identified preserved specimens of Actineda from Rio Apa (Paraguay) and from 
Buenos Ayres with the European species, with the remark “parum ab Europea 
diversa”*. It therefore seems that A. baccarum, L. (=A. vitis, Schrank, =TZromd. 
cornigerum, Hermann), is one of those fundamental and characteristic types which 
occupy an extremely extensive geographical area, a fact I have discussed at length in 
the “ Introduction” to the present memoir. 
Fam. TETRANYCHIDA, Kramer. 
TETRANYCHUS, Dufour. 
1. Tetranychus guatemale-nove. 
Tetranychus guatemale-nove, Stoll, antead, p. 8, Tab. VI. figg. 1-1 ¢. 
Hab. GuateMALA, near the city. 
2. Tetranychus dugesi. 
Tetranychus dugesii, D. Cano y Alcacio, La Naturaleza, vil. p. 197, t. 2. figg. 1-5. 
Hab. Mexico. On Medicago denticulata, Willd. 
Fam. HYDRACHNIDA, Neuman. 
The corrections in the synonymy of the species of this family described by me are 
made on the competent authority of Herr Koenike of Bremen, who, at my request, has 
favoured me with his opinion on them. 
ATAX, Fabr. 
1. Atax alticola. 
Atax alticola, Stoll, antea, p. 9, Tab. VII. figg. 1-lg. 
Atax septem-maculatus, Stoll, antea, p. 9, Tab. VIII. figg. 1-1 e. 
* A. Berlese (Acari Austro-Americani, p. 11) identifies his American specimens with Acarus vitis, Schrank, 
which he considers to be synonymous with Z’rombidium cornigerum, Hermann. But as Schrank himself, in 
his description of A. vitis (Enum. Ins. Austr. indig. p. 519. no, 1067), says that it differs from A. baccarum, 
L., only by the disposition of the hairs on the legs, I think that we must regard A. vitis, Schrank, and Acarus 
baccarum, L., as belonging to one and the same species. | 
