00 american hymenoptera. 



Group M, 



Rair on inner side of basal joint of hind tarsi black or fascons. 



Hair of anterior part of thorax deep fulvous • . . • 1. 



Hair of anterior part of thorax pallid, at most slightly yellowish or pale ochra- 

 ceous (except sometimes quite fulvous in 31. grindelifi;) 2. 



1. Largest, length of anterior wing 13 mm. ; similar in appearance to M. comau- 



che ; species of Texas Melissodes grandissima Ckll. 



Larger than dentiventris, length of anterior wing about 11 mm.; hair of disc, 



of thorax black; abdomen with two pale fulvous hair bands. 



M. coloradensis Cress. 

 Smaller, length of anterior wing a little over 8 mm.; hair of thorax above 



nearly all fulvous ]»I. dentiventris Smith. 



2. Head extremely broad ; eyes pale bluish grey; tegulfe black; abdomen with 



three broad white hair bands M. pallidicincia Ckll. 



Head ordinary 3. 



3. No light hair at sides of fifth abdominal segment 4. 



Some light hair at extreme sides of fifth abdominal segment 5. 



4. Larger; tegulge with a tuft of pale hair; eyes blue-grey. .M. niysops Ckll. 

 Smaller; tegulis with a tuft of black hair; eyes light green; hair of labrum 



black M. cont'usa Cress. , 



5. Larger 6. 



Smaller; abdominal bands white or yellowish white (sometimes pale also in 



grindelise, hut then size comparatively large 7. 



6. Abdominal bands fulvous ; tegulse with some black hair; hair of labrum light. 



M. griiideliae Ckll. = ntontaua Cress. 

 (The ^ Montana is grindelix, but not the male.) 

 Abdominal bands creamy-white; tegulse without black hair (Arizona). 



M. iiigrosignata Ckll. 

 {31. nigrosignata varies in color of hair of middle tarsi, which, though typi- 

 cally black, may be largely pale. A more extreme variety, from the 

 same locality, has been named var. pallidosignata Ckll. This has seg- 

 ments 2-4 of abdomen practically covered with pale ochreous hair, and 

 hair on outer side of middle tarsi all yellowish white. It is easily 

 known from grindelise by having the hair on tegulse all light.) 



7. Tegulse with some very short black hair; hair of middle tarsi black. 



W. pei'plexa Cress. 

 Tegulse without black hair 8. 



8. Hair of middle tarsi white ; scopa of hind legs very long. 



M. interniediella Ckll. 



Narrower than intermediella ; abdominal banding like that of M. pallidicincta ; 

 distinguished from sphseralceie by broader abdominal bands, and hind 

 margin of first segment not hyaline, etc. ; abdomen much narrower 

 than in Xenoglossodes excurrens M. pecosella Ckll 



Rather more robust than pecosella ; flagellum bright ferruginous beneath: 

 occuring at lower altitudes than pecosella. 



M. peeosella Terbesinarnm Ckll. 



Narrow species, looking like Tetralonia lippise ; abdominal bands white (almost 

 bluish white), not creamy as in pecosella, etc.; tegula? light fulvous 

 (Arizona) Wl. duplocincta Ckll. 



