76 AMERICAN HYMENOPTERA, 



Seeies 1. — Flafrellum dark, not red beneath. 

 Abdomen beyond middle of second segment black, with long black hair, and no 

 light hair or bands; lateral margins of yellow of clypeus not notched. 



Tetralonia intrudeus (Cress.). 



(See also Tetralonia actuosa Cress., peculiar for the ventral teeth or keels near 



apex of abdomen. The northern form of actuosa recorded by Viereck 



appears to differ a little, in that the first r. n. joins the second s. m. at 



middle, whei'eas in typical actuosa it joins it about or even beyond the 



beginning of the last third.) 



Abdomen beyond middle of second segment with pale hair, and more or less 



evidently banded .1 



1. Upper part of clypeus black ; flagellar joints with light dots beneath. 



JVIeIi$»so<Ie!s niicrosticta Ckll 

 Upper part of clypeus not black ; flagellar joints without light dots beneath. .2 



2. Larger; pubescence of thorax above fulvous ; hin<i niargins of abdominal seg- 



ments not hyaline Tetralonia Iioiiesita (Cress.) 



Smaller; pubescence of thorax above pallid, with a yellowish tint; hind mar 



gins of abdominal segments broadly hyaline. 



IVIelissodes conf'nsa Cress. 

 Smaller than con/»so ; abdomen not conspicuously banded ; middle and hind 



tarsi remarkably long and slender, which distinguishes it at once from 



microsticta or confusa (Arizona) M. leuiiitarsis Ckll. 



Series 2. — Flagellum more or less red beneath (all Melissodes.) 



Scutellum without black hair 1. 



Scutellum with black hair (only a little in otomita) ; hair on inner side of basal 

 joint of hind tarsi pale or ferruginous 3. 



1. Hair of thorax snow-white ; nervures honey color ...... -itl. siiowi Cress. 



Larger than snowi ; hair of mesothorax snow-white, of scutellum yellowish; 



clypeus greyish white; labrum black, with a large light spot (Arizona). 



M. prselaiita Ckll. 



Smaller than snowi or true agilis {snowi and agiiis are the same size), and dis- 

 tinguished by pubescence ochreous tinted (as in agilis), and labrum 

 entirely black (in snowi it has a very large yellow spot) ; eyes light 

 green. Very much smaller and quite different from rivaJis (Colorado, 

 Arizona) M. agili$» siibagilis Ckll. 



Hair of thorax ochreous 2. 



2. Abdomen without pale hair bands; hair on inner side of b. j.* black. 



desponsa Sm. 

 Abdomen with pale hair bands; hair on inner side of b. j. ferruginous. 



rivalis Cress. 



3. Hair of thorax whitish or cinereous and black 4. 



Hair of thorax ochreous and black 7. 



4. Antennae comparatively short ; small species; bind margins of abdominal seg- 



ments 2-5 broadly covered with bright orange-fulvous hair. 



otouiita Cress. 

 Antennae long ; larger species 5. 



■•■• "b. j." in these tables means basal joint of hind tarsi. 



