128 UNIVERSITY OF COLORADO STUDIES 



Bombus huntii Greene. Newcastle, August 2 and 3, at Cleome or "bee plant" 

 (R.); Meeker, August 9, at Cleome serrulata (R.); ten miles east of Meeker, August 

 19, at Solidago (R.); 2§ miles south of Axial, August 13, a male at Rudbeckia ampla 

 (R.). 



B. centralis Cresson. This is exactly like juxtus Cress., in nearly all respects, 

 but the worker (female not seen by me) has black hair on the middle of the basal part 

 of the abdomen. Mr. Franklin (in litt.) states that centralis is "a freak specimen" of 

 juxtus, and as the name has priority, uses it for all juxtus. Five workers before me 

 all agree with Cresson's description of centralis, and seem to represent a valid geo- 

 graphical race, which must extend (at lower altitudes than B. flavifrons) from Cali- 

 fornia to western Colorado. Meeker, August 9, males and workers at Cleome 

 serrulata (R.); Newcastle, August 3, at Cleome (R.); Rifle Gap, August 4, at "bee 

 plant" (R.). 



B. nevadensis Cresson. 2% miles south of Axial, August 13, a male at Achillea 



(R-). 



B. appositus Cresson. Newcastle, August 2, male at Carduus (R.). 



B. fervidus (Fabricius). Rifle Gap, August 4, at Helianthus and at "bee plant" 

 (R.); Meeker, August 9, male at Cleome serrulata (R.). One of the Rifle Gap speci- 

 mens (worker) has the thoracic band very poorly developed. 



B. occidentalis howardii (Cresson). Ten miles east of Meeker, August 19, 

 males at Solidago (R.). The hair on the apical segments of the abdomen varies from 

 whitish to pale reddish. 



Melissodes agilis Cresson. Rifle Gap, August 4, at Helianthus (R.). The speci- 

 men is a male, peculiar for its rather large size (about 12 mm. long), labrum black 

 with a large whitish spot, mandibles without light spots at base, face unusually broad, 

 flagellum very slender and pale, apical plate of abdomen with the notches very near 

 the end. I had some thought of treating it as a distinct species or subspecies; but 

 it is in other respects so distinctly agilis, and that species is so variable, that segregation 

 does not seem justifiable. The slender pale flagellum associates it with agilis rather 

 than with menuacha. 



M. mysops Ckll. 2! miles south of Axial, August 13, at flowers of Rudbeckia 

 ampla, one female (R.). 



Megachile sexdentata Rob. Rifle Gap, August 3, male and female at Helianthus 

 (R.). The male is the insect which passes in Colorado and New Mexico for M. 

 pruina Smith. M. sexdentata differs in certain respects from pruina, but is at least 

 very closely allied. 



M. cleomis Ckll. Meeker, August 9, at Cleome serrulata, one male (R.). 



M. pugnata Say. Ten miles east of Meeker, August 19, at Solidago, one male 

 (R.). The specimen is unquestionably pugnata, but the hair of the meso thorax 

 above is wholly pale, and the first recurrent nervure meets the first transverso-cubital. 

 The change in the venation is especially interesting, as ordinarily it would be con- 

 sidered a good specific character. 



