Nov., 'CK;] KXToMoi.or.rrAT, XKWS 377 



Notes and Descriptions of Some Trypoxline Wasps. 



BY S. A. ROHWER, Boulder, Colo. 



GROUP FRIGIDUM. 



The group of Trypoxline wasps of which frigidum F. Sm. 

 may be taken as the type consists of small (about 8 to n 

 mm.), slender, black, little pubescent species. There is no 

 enclosed area on the metanotum, but in some species there 

 is a strong central furrow; the hind trochanters of the males 

 are simple. The following table will separate the species 

 which are known to belong to this group: 



Females i- 



Males . . 4. 



1. Metanotum without a median furrow (clypeus with a narrow tooth 



which is sometimes bidentate) frigidum F. Sm. 



Metanotum with a strong median furrow 2. 



2. Clypeus regularly rounded on the anterior margin . . . regulare Vier. 



Clypeus with a broad slightly emargmate tooth apicale Fox. 



Clypeus with a narrow tooth 3. 



3. Striae of the metanotum almost transverse ; first abdominal segment 



but little longer than the second, and with a much shorter 

 petiole ; dorsulum with distinct punctures ; shining. 



nigrellum Roh. 



Striae of the metanotum mostly longitudinal ; the first abdominal seg- 

 ment about twice as long as the second, and with a long peti- 

 ole, nodose at the apex ; dorsulum opaque, very closely and 

 finely punctured bidentatum Fox. 



4. Metanotum with a distinct middle furrow (the clypeus with a narrow 



bidentate projection) bidentatum Fox. 



Metanotum without a distinct median furrow 5. 



5. Dorsulum shining, with scattered punctures ; no furrow from the an- 



terior ocellus subfrigidum Roh. 



Dorsulum opaque, with very fine close punctures ; a distinct furrow 

 from the anterior ocellus frigidum F. Sm. 



Trypoxylon frigidum F. Smith. 



I have collected this species from the following localities in 

 Colorado : Florissant, June 1 1 to July 24, most of the speci- 

 mens were collected on the foliage of Ribcs rallicola; one fe- 

 male Boulder, September 24, 1906; one female Troublesome, 

 June 8, 1908, altitude 7345 feet. 



Fox (Tr. Am. Ent. Soc. XYII1, p. 143, June, 1891) gives the 



