HENRY J. FRANKLIN. 205 



eluding the corbicular fringes, and are present to some extent on the 

 venter of the abdomen and on the sting palpi. These hairs vary 

 greatly in length and fineness between different species. They grade, 

 on the tibiae, completely into the long slender spines described under 

 number eight below. 



5. Long hairs with long branches (fig. 29). These hairs are shorter 

 and finer than the long branched hairs just described, and are thor- 

 oughly intermixed with them on the head and thorax. On these por- 

 tions of the body, they are with some species, of a different color from 

 that of the coarser kind (<?. g., occiput and dorsum of thorax of but- 

 teli, handlirschi, ntelatwpygus, tnixtus, sitkensis and volucelloides) , 

 though, as a rule, the two kinds, wherever present together on the 

 same part of the integument, are for the most part of the same color. 

 When the two kinds are of different colors, the longer coarser kind is 

 much the darker, and the general color resulting from the mixture of 

 the two is grayish. 



These hairs with long branches are also present to some extent on 

 the venter of the abdomen, on the proximal ends of the legs, on the 

 tarsi, and in the corbicular fringes, being everywhere mixed with the 

 coarser kind. Almost every gradation between these two kinds is 

 present, but these gradations are neither numerous nor conspicuous. 



6. Minute, unbranched hairs with flat, strongly widened and truncate 

 distal ends. These hairs are confined to the hind femora and tibise, 

 clothing the entire inner faces of the latter, but being present only on 

 the distal halves of the inner faces of the former. 



7. Minute spines with conical bases. These are found only on the 

 wings and are, for the most part, confined to those portions distad of 

 (beyond) or behind the veins. 



8. Long and slender acicular spines. These are to be found almost 

 entirely on the front and middle tibiae and on the metatarsi and they 

 are the most numerous of all the spines present on those parts of the 

 body. There are all gradations between these spines and those next 

 described. 



9. Powerful spines with blunt points, borne on the distal ends of all 

 the tarsal segments except the last and on the front sides of the hind 

 metatarsi. 



10. Stout, flattened and somewhat curved spines placed in a single 

 transverse row on the distal end of each hind tibia of the queen and 

 worker. Species of Psithyrus do not have these spines. See figs. 12 

 and 48. 



11. Compound spines. Two of these are present on the distal end 

 on each hind tibia and one on the distal end of each front and each 

 middle tibia in all groups and castes (figs. 12, 20 and 48). All of these 

 spines are laterally denticulate or spinulate. This, together with the 

 fact that they are the largest spines which bumblebees have and are 



TRANS. AM. ENT. SOC, XXXVIII. 



