426 [Jvnk 



Catalogue of HYMENOPTERA in the Collection of the Entomological Society 

 of Philadelphia, from Colorado Territory. 



BY E. T. CRESSON. 



[Continued from page 313.) 



Fam. FORMICID^E. 



Genus FORMICA, Linn. 



1. Formica rufa. Linn. 



Formica rufa, Linn. Faun. Suec. n. 1721 ; Syst. Nat. i, p. 962. Smith, Cat 

 Brit. Aculeate Hymen, p. 4 (with full synonymy). 

 Two $ . seven $ , one % . specimens. 



2. Formica aterrima, n. sp. 



Black, opaque, abdomen shining; antennae and legs tinged with fuscous: 

 wings tinged with fuliginous, darker at base. 



Male. — Black, opaque; head and thorax clothed with a short, sub- 

 erect, palish pubescence; mandibles tinged with piceous ; frontral area 

 triangular and very slightly shining; clypeus prominent, faintly cari- 

 nate down the middle, the anterior margin entire ; antennae black, the 

 flagellum tinged with fuscous. Wings tinged with fuliginous, darker 

 towards the base ; neuration as in F. rufa % . Legs tinged with fus- 

 cous, sericeous. Abdomen ovate, piceous-black, shining, somewhat seri- 

 ceous, the extreme apex luteous ; scale of the petiole subquadrate. more 

 or less emarginate above. Length 4} lines. 



Five specimens. Closely resembles F. rufa % , but is at once dis- 

 tinguished by the black legs; the antennae are rather more robust, and 

 the wings much darker towards the base ; the body is similarly shaped, 

 but more robust. 



3. Formica herculanea, Linn. 



Formica herculanea, Linn. Faun. Suec. n. 1720; Syst. Nat. i, p. 962. Smith, 

 Brit. Mus. Cat. Hym. vi, pp. 10 & 53 (with full synonymy). 

 Five $ , five $ , seventeen % , specimens. 



Genus MYRMICA, Latr. 

 1. Myrmica occidentalis, n. sp. 



Ferruginous; head and thorax densely striated; wings hyaline; abdomen 

 subglobose, polished, the segments fringed with glittering pubescence. 



Female. — Ferruginous ; head and thorax opapue, thinly clothed with 

 a pale glittering pubescence, and densely striated longitudinally, the 

 striae on the thorax much the finest ; head large, quadrate, much 



