THE CANADIAN ENTOMOLOGIST. 173 



In this paper Gnai/iias aoieatus and ovatus and Xaiithidmm den- 

 tarice are described as new, and the male of Centrias erigeronis is de- 

 scribed for the first time. 



After Cephen was characterized as given in the table, I suspected that 

 it might be the same as Microiwmada, Ckll., but I could not identify that 

 genus without getting specimens of the type, N. modesta, for examination. 

 IV. modesta has the cell III5 strongly narrowed above, cell III1+2 less ob- 

 tuse, and the vein a ends a little before or is interstitial with Vg. The 

 front cox£e have a tubercle above the spine. The other structural charac- 

 ters are quite similar, and show that the two genera are closely related, 

 but the venation is so different that I have decided to let Cephefi stand. 

 N. /ervida, Sm., also belongs to Cepheti. 



Herninoitiada, Ckll., like Microiiomada, Ann. Mag., N. H., VII., 

 10 : 42-4, 1902, I would raise to generic rank. Of 37 specimens in my 

 collection, 9 have three submarginal cells in one or both wings. 



Vein ;v«, usually wanting in HoJiinomada, I have also found want- 

 ing in N. Cressonii (i) and Sayi (i). Vein III5 I have found wanting in 

 Gnathias ciuieatus (i), Centrias Americantis (i), rubicundus (i), Nomada 

 parva (i). 



I have to thank the authorities of the American Entomological So- 

 ciety for the privilege of examining co-types of N. affabilis and bella and 

 specimens of N. modesta. Mr. Viereck noted several points in which the 

 N. Y. specimen of N. affabilis differed from the co-type sent me for ex- 

 amination. 



In his early descriptions Mr. Cresson mentions the structure of seg- 

 ment 7 of the males, and in his later ones notes the form of the joints 

 of antennae. 



Females. 



Mandibles bidentate; joint 3 shorter than 4 ; vein a before Vg ; head 

 and thorax red ; sutures, depressed and concealed portions 

 black Gfiathias. 



Mandibles simple i . 



1. Front coxse simple; rarely (N. denticiilata) with short, indistinct 



spines 3. 



Front coxae with long pubescent spines ; abdomen distinctly punc- 

 tured 2. 



2. Joint 3 longer than 4; vein a beyond, or interstitial with, Vg ; cell 



Illg subquadrate, III1+2 obtuse j joint i of labial palpi twice as long 



