1903] MELAXDER: — XORTII AMERICAX SPECIES OE AMMOPHILA jcy 



same as Dahlbom's species; procera Lap. is not procera Dahlb., but is the other 

 sex of his intcrcepta and both are synonyms of nigricans Dahlb.; gracilis Cam. is 

 not gracilis Lep., while the Canadian form of same name seems to be a third 

 species. 



With such well-known and long established names as cementaria, gryp/ius, 

 procera, robusta, macra, anoviala, etc., untenable, the future student will hesitate 

 before describing new species. However the Mexican and Central American spe- 

 cies of Peter Cameron seem valid and in little danger of confluence. The stumbling 

 block of the earlier describers has often been the association of the sexes, since a 

 distinct dimorphism often prevails. Generally the males are more slender, more 

 hirsute, and more brilliantly marked than the females, and in those species with the 

 abdomen partially red the males frequently have the black encroaching dorsally 

 as a median line. Their clasping sexual organs and the narrow and straight-sided 

 face are distinctive of this sex. 



Of the species of the United States some difficulty might be experienced in 

 differentiating between certain forms. For this reason a few supplementary notes 

 on the common species are added : — 



vulgaris is a small species, about three fourths of an inch in length. The 

 mesonotum of the female generally has a deep median furrow. The striae of the 

 metanotum are close together, oblique and well-cut, and are generally connected by 

 a median line. 



juncca is founded on a slender male with very fine transverse metanotal striae. 

 The central portion of the disc is sometimes confusedly punctate and slightly hairy. 

 It is a larger form than vulgaris. 



strenua is about one inch in length and has complete transverse striae on the 

 metanotum not quite so well marked as in vulgaris but rougher than m. juncea. The 

 anterior striae tend to become oblique. The female has a short narrow impressed 

 line on the mesonotum. 



urnaria. The obsolete striate arrangement of the punctures near the tegulae 

 is quite characteristic and fairly constant in this species. The rather coarse striae 

 of the metanotum are more or less oblique and frequently become rugulose on the 

 disc as m juncea. 



abbreviata is quite distinct among the local species by the acuminate clypeus 

 of the male, the short pale golden macule of the mesopleurae, and the black 

 abdomen. 



nigricans also has the abdomen mostly black but the pleurae are entirely black 

 and the wings darkened. 



extremitata is quite distinct by the yellowish wings. The thorax of the female 

 is matte-black and the abdomen contains a brighter red than in the other common 

 forms. 



