CHARLES W. METZ. 103 



32) . Seventh ventral plate also unique ; lateral wings not separate at- 

 tachments, but enlargements of the proximal arms ; apical portion of 

 the lateral margin with long spine-like hairs ; basal portion with tuft 

 of fine hairs, (fig. 36). Eighth ventral plate merely a triangular body, 

 without apical pedicel, (fig. 34). 



Female. — Easily known by its large size and entire lack of yellow 

 markings. As large, or larger than male which it resembles in gen- 

 eral characters, but scape normal. 



Sculpture. — Puncturation much more light than in male. Enclosure 

 of propodeum smooth, lateral faces slightly punctured instead of rugu- 

 lose. Abdomen practically impunctate. 



Yellow Markings. — Entirely lacking. 



Habitat. — Apparently not restricted in the United States. 

 This species has been reported from nearly every portion of 

 the country where much collecting has been done, but it is 

 not common in any locality. 



This, the largest species of Prosopis in North America, is 



so entirely different from any other known species in this 



country that there is no chance for confusing it, in either 



sex. Just the range of variation in the species is not known. 



Eight specimens before me from Colorado, New Mexico, 



and South Dakota show practically none, but in puncturation 



they all differ considerably from the original descriptions, 



which state, "basal segment of abdomen very smooth and 



shining " for both sexes. As Smith's work was probably 



done largely with a hand lens this apparent difference may 



not be true. 



PROSOPIS POTENS n. sp. 



Male. — Distinguished by its short, broad head, stout clypeus, both 

 of which resemble P. basalts in form, by its short, heavy lateral face 

 marks, and by its very distinct genitalia. 



Length about 6-7 mm. ; stout, head very broad ; clypeus broad as 

 long, somewhat narrower at base than lateral areas at same level ; 

 lateral areas unusually broad ; supraclypeal area broader than long 

 below base of antennal sockets. Scape stout, concave posteriorly. 

 Thorax stout ; metanotum comparatively long, two-thirds length of 

 scutellum ; propodeum short, with no distinct superior face, slanting 

 oflf directly from base. 



Sculpture. — Puncturation of entire body remarkably light. Front, 

 and part of vertex with small, shallow, close punctures, not extending 

 onto occiput or cheeks ; pronotum not prominent, indistinctly punc- 

 tured ; mesoscutum sparsely punctured with small, round punctures, 



TRANS. AM, KNT. SOC, XXXVII. 



