590 GEOLOGICAL SURVEY OF THE TEREITOKIES. 



I), sefnicincta, Hagen, Synop., 176, 5. 



A fragment of a female similar to my specimens, but the fiiscesceut 

 color extending upon the anterior wings as far as on the posterior wings. 

 I never saw similarly -colored specimens from the region east of the 

 Eocky Mountains. 



Rahitat. — Foot hills, Colorado (Lieutenant Carpenter). The species 

 is not rare in the States east of the Mississippi as far south as Mary- 

 land. 



In the last report (1872, p. 728), I noticed from the Yellowstone region 

 D. assimilata, D. scotica, and D. vicina. The first species is, as I now 

 perceive, my J), decisa ; the other two are no more at hand?- 



Subfamily COEDULINA. 



EPITHECA. 



U. semicireularis, De Selys, Synop. des cordulines, 61, 37. 



Dark brassy-green ; occiput and labium black ; rhinarium and labium 

 pale-yellowish ; on each side of the front a large luteous spot, connected 

 sometimes on the lower edge of the front in a narrow luteous band, inter- 

 rupted in the middle by a small black interval; eyes black behind; 

 thorax dark brassy-green, clothed with long grayish-brown pile before 

 the sinus, sometimes transversally fulvous, sometimes not ; the sides 

 with two ill-defined luteous spots; feet entirely black; abdomen brassy- 

 black, a large fulvous spot on each side of the second segment, a smaller 

 one on the third segment (often wanting in the males) ; segments 4 to 8 

 with a small fulvous basal spot on each side (always wanting in the 

 Colorado specimens) ; appendages of the male black, the superiors long, 

 subcylindrical, cariuate inferiorly and exteriorly ; viewed from above, 

 the basal half is convex, straight, tapering, divergent ; the apical half 

 is bent slightly outward, then inward, subexcavated before the 

 pointed end; viewed laterally, the appendages are curved somewhat 

 downward, the apex laminate, the lower edge with a small external 

 basal tooth, beyond the middle a rounded lamella, and between them 

 the internal edge produced in form of a larger rounded lamella. Both 

 lamellae, viewed from above, appear as lateral projections ; inferior ap- 

 pendage more than half the length of the suj)eriors, triangular, bluntly- 

 pointed, concave below, recurved, the tip minutely uncinate above; 

 appendages of the female long, stout, cylindrical, black ; vulvar lamina 

 half the length of the segment, yellowish, quadrangular, somewhat erect ; 

 apical margin rounded, split in the middle ; wings hyaline, or with a 

 yellowish tinge (Vancouver Island specimens) ; costa lined with yellow ; 

 extreme base of the hind- wings subfumose ; membranula blackish-gray, 

 white at the base ; antecubitals, 7-8 ; postcubitals, 6-7 ; triangle in some 

 specimens with a transversal vein in one or both hind-wings. 



Length of the body, 50-46 millimeters ; alar expansion, 80-60 milli- 

 meters ; pterostigma,2^ millimeters. 



Sahitat. — Gulf of Georgia (by Mr. A. Agassiz, the male type described 

 by De Selys), Yancouver Island, in July (Mr. Crotch); Colorado, on 

 Twin Lake and Arcade Eiver, August 1 to 16 ; Pacific slope, August 16 

 to September 6 (Lieutenant Carpenter) ; Ogden, Utah (Mr. C. Thomas). 

 A careful study of the male type in the collection of the museum shows 

 the anterior femora entirely black, not '•'• presque noirdtre,''^ as in De 

 Selys's descrix^tion. This character is very important as difference from 

 U. forcipata. The words of the description, "t7e crois distinguer en 

 dessons tine sorte de dent suhmediane analogue a ce que Von voit chez E. 



