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 obscuripcs, 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) . This is much 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 "espece extreme- 

 ment douteuse et indechiffrable," 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. 



