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WHEELER: ANTS OF THE GENUS FORMICA. 565 
All the foregoing Mexican forms, though occurring as far south as 
latitude 20° N., were found only at rather high altitudes. In addition 
to these four forms and F. perpilosa, described on p. 421, several other 
Formicae have been recorded as occurring in Mexico by Forel in the 
“Biologia Centrali-Americana,” namely F. fusca var. subsericea, F. 
rufibarbis, F. neorufibarbis, which Forel regarded as a var. of rufibarbis, 
F. rufa obscuripes, and F. incisa. Concerning these forms I venture 
the following remarks :— 
1. F. fusca var. subsericea is recorded from Durango, 8,100 ft. 
(Forrer), Atoyac in Vera Cruz (Schumann), and Moyoapam (Coll. 
Saussure). Thisismuch more probably F. fusca var. argentea Wheeler. 
2. F. rufibarbis is cited from Sonora (Morrison) and Omilteme 
in Guerrero (H. H. Smith). This is probably the form which I have 
called F. rufibarbis var. occidua and not the typical specific form which 
is Palaearctic. 
3. F. rufibarbis var. neorufibarbis Forel, which is recorded from 
Durango, 8,100 ft. (Forrer), is probably the var. gnava Buckley. 
4. For F. rufa obscuripes only the locality “ Mexique (Brinkmann) ”’ 
is given. This form may, perhaps, occur in the high mountains of 
Northern Mexico, but I am inclined to believe that the specimens to 
which Forel refers belong to some other rufa form or to some member 
of the microgyna group. 
5. F. incisa was described by F. Smith from a female specimen, 
with the locality “Mexico.”’ As Forel says, it is an “espéce extréme- 
ment douteuse et indéchiffrable,”’ but it can hardly be the female of 
some form of F. rufibarbis, as he suggests, because the coloration of 
this species is very different. 
