HENRY J. FRANKLIN, 201 



In South America, the most variable species have the 

 greater part of their habitat in the highland of the Andes. 



In the coloration of the pile, those colors which may, in 

 general, be classed as ferruginous, rufous and white are, as a 

 rule, brought out by high altitudes and also by Arctic or sub- 

 Arctic latitudes, only traces, at most, as a rule of these colors 

 being found on strictly lowland forms either in tropical or 

 temperate climates. High altitudes appear to have a much 

 stronger influence in bringing out these colors than do high 

 latitudes, as among the New World species, these colors attain 

 their maximum among the Cordilleras of the Andes in Ecua- 

 dor and Peru where bumble-bees reach the highest eleva- 

 tions. Traces of ferruginous or rufous pile on lowland tem- 

 perate or tropical species (e. g. — affinis, second dorsal seg- 

 ment of worker and male abdomen ; fraiernus, apex of male 

 abdomen ; separatus, second dorsal abdominal segment of 

 all sexes) may, perhaps, be taken to indicate a mountain 

 inhabiting ancestry. In this connection, the coloration of 

 dahlbomii and emilicB seems to indicate that they have, in 

 comparatively recent times, extended their habitat into east- 

 ern Argentina, southern Brazil and Uruguay. 



Yellow is more or less strongly suppressed in the colora- 

 tion of the pile of tropical species of the genus Bombus. This 

 suppression is marked in both lowland and highland forms, 

 and is so strong that this color is entirely wanting in a large 

 percentage of the species in the tropics of the New World. 

 In the lowlands this has resulted in some cases in the pro- 

 duction of entirely black species {kohli, niger, atratus, brevi- 

 villus, solus). In the mountain regions black is less preva- 

 lent, for the rufous or the white pile on the mountain forms 

 replaces the suppressed yellow more or less. 



Arctic forms have noticeably longer and finer pile than 

 have the species of warmer climates, and mountain species 

 appear to have, as a rule, finer hair than the lowland ones. 



The fact that, in both the Old and the New World, the 

 species of the subgenus Bombias are, as a rule, confined in 

 their habitat, for the most part, to mountainous regions, 

 is interesting and perhaps suggestive. Auricomus, separatus 



TRANS. AM. ENT. SOC, XXXVIII. (26) 



