GEOLOGICAL SURVEY OF THE TERRITORIES. 267 



arid coloring somewhat similar to A. purpivrascens, (Uhler,) but smaller 

 and slenderer in all its parts. Face white, the transverse suture below 

 the front fuscus ; tips of the mandibles piceous; palpi pale, the penul- 

 timate joints of the maxillary palpi striped with purple above ; anten- 

 nae long and slender, reaching nearly to the extremity of the ovipositor, 

 dusky; cranium cinereous, with the vertex, and a line extending back 

 from each eye, dull white. Pronotum short, not carinated, a slight 

 transverse incision near the front ; two oblique dorsal impressions, dark 

 and very narrow ; surface smooth, lurid ; a large black spot occupying 

 the central portions of the sides behind the transverse incision ; lateral 

 margins broadly, and anterior margins narrowly bordered with pale 

 yellow; posterior angles tipped with piceous black. Elytra hid beneath 

 the pronotum. Abdomen dull purple, somewhat darker along the sides. 

 Ovipositor slightly curved beyond the middle, piceous at the tip ; cerci 

 slender, hairy ; beneath dull white. Anterior and middle legs short ; 

 femora slender and straight ; posterior legs very long and slender ; fe- 

 mora and tibise, each the length of the body, omitting the head ; all pale 

 purplish-yellow; femora smooth; tibia} with spines irregularly placed on 

 the angles, also on the rounded portion, black at the tips. The spine 

 above the anterior coxa pale, slender, and bent abruptly downward. 



Length 1.13 inches; pronotum .26 inch; posterior femora .93 inch; 

 ovipositor .75 inch. 



Habitat : Southern Colorado, on elevated grassy terraces near the 

 mountains and the parks. Named in honor of Mr. James Stevenson, 

 a member of the expedition, who has for a number of years accompanied 

 Dr. Hay den in his western explorations, and has been a diligent collector 

 of specimens in all departments of natural history. 



A. minutus, Thos. Syn., A. minutus, Thos. (Proc. Acad. Nat. Sci., 

 Phila., 1870, p. 75.) — Male: Similar in coloring and appearance to the 

 A. Stevensonii. Face mottled with purple ; a dark spot below each eye ; 

 a narrow line running back from the upper corner of each eye; cranium 

 cinereous; head somewhat covered by the pronotum. Pronotum short, 

 rounded, smooth ; transverse incision almost obliterated ; oblique dorsal 

 impressions irregular; dorsal portions cinereous ; sides with a triangular 

 black spot, interrupted by light spaces, broadly margined with dull white; 

 lateral angles tipped with pieeous-black. Elytra short, extending over 

 the second abdominal segment; margins pale yellow, central portions 

 brown. Abdomen cinereous, a darker line along the sides; notch of the 

 sub-anal plate very small ; appendages small, hairy ; the tip of the last 

 dorsal segment strongly bifid, denticulate. The cerci (I use this term 

 for those appendages supplying the place of cerci) slightly bent, bifurcate. 

 Legs same color as the abdomen and cranium ; anterior pair quite short ; 

 the middle pair a little longer ; the posterior very long, femora marked 

 with a dark line along the upper carina ; tibiae slender, spines tipped with 

 brown. Antennas at least twice as long as the body. 



Length, .75 inch ; ^posterior femora, .62 inch ; elytra, beyond the pro- 

 notum, .1 inch. • 



Female : Similar to the male in appearance, coloring, and size. Cerci 

 small, hairy. Ovipositor bent, slightly narrowed in the middle; brorcn 

 at the tip. Length as in the male ; ovipositor, .55 inch. 



Habitat : Elevated grassy terraces in Southern Colorado, South Park. 



Some specimens of these two species have, on the under side of the 

 posterior femora, about four or five abortive spines, especially the older 

 or more mature ones. Sometimes the places of these spines are indicated- 

 by mere points, visible only under a glass. This fact may be important 

 in fixing the position of this genus, which is evidently one of transition. 



