AMERICAN HYMENOPTERA. 305 



we have seen are grouped together, but some relationship at least 

 is expressed in the following key for the separation of the males. 

 The descriptions of the new species have been interpolated as near 

 to their relatives as is practicable. The number of undescribed 

 forms occurring in the Southwestern States is remarkable. The 

 males are caught mostly at lights which they seek in their nocturnal 

 flights. The females, however, are much more seclusive, and have 

 to be sought for on the hot, arid sand during the day-time. 



Mesosternum with a pair of strong projections near its anterior border. 



(Subgen. OdoiitopliotO|>*is Viereck) 2. 

 Mesosternum with a pair of crenulate. longitudinal ridges, but with no strong 



tooth anteriorly 11. 



Mesosternum completely unarmed (PhoSopsis Blake) 14. 



2. Ths projection of the mesosternum acutely pointed, more or less beak-like 



and longitudinally placed, though sometimes small ; wings hyaline. .3. 

 The projections at most truncate pyramidal, but not pointed, rather trans- 

 verse ; wings with brown clouds 10. 



3. Petiole of abdomen rather nodose, constricted apically, and with stronger 



punctures than those of the second segment 4. 



Petiole nearly sessile with the second segment, not nodose and nearly impunc- 

 tate; abdominal segments fringed with plumose hairs 8. 



4. Petiole twice as long as broad, with fine punctures on the disc ; all the abdomi- 



nal segments fringed with strongly plumose white hairs. 



Westcoltii sp n. 

 Petiole shorter and with coarser punctures 5. 



5. Mesonotum with fine scattered punctures 6. 



Mesonotum with close deep punctures, the grooves abbreviated on the anterior 



half; veins thin, testaceous, wings hyaline 7. 



6. Parap'sidal grooves extending nearly the whole length of the notum ; veins 



strong brown, wings tinged with brown pudica sp. n. 



Grooves wanting ; wings hyaline, veins testaceous grain sp. n. 



7. All the abdominal segments fringed with plumose hairs; legs and antenna; 



testaceous; hind ocelli nearer the eyes than each other. 



Erebus sp. n. 

 Only the second abdominal segment with a fringe of plumose hairs, the 

 remaining vestiture dense and long, however; ocelli nearer each 

 other than the eyes; antenna? and part of femora fuscous. 



melicausa Blake. 



8. Abdomen with setigerous punctures, fuscous apically ; femora blackened at 



tip eoneolor Cress. 



Hairs of abdomen not arising from punctures; smaller species with pale 

 legs 9. 



9. Mesothorax with strong punctures and complete grooves; metathorax reticu- 



lated over all above hamala sp. n. 



Mesothorax with shallow punctures and abbreviated grooves; metathorax 

 with elongate basal areas trila sp. n. 



TRANS. AM. ENT. SOC, XXIX. (39) OCTOBER, 1903. 



