GG 



APPENDIX. 



1. Didea laxa n. sp. ,^ 2 . 



The greenish or yellow cross-bands are attenuated on the sides and come in 

 contact with the lateral niargins of the abdomen. Length, 11-13 m. m. 



Female. — Face yellow, with a broad, brown stripe, front and vertex black; 

 the former with gray dust on both sides. Antennae black. Thorax blackish - 

 green, shining. Scutellum dull brownish-yellow, with a slight greenish or 

 bluish metallic lustre; pleurae with a whitish spot, beginning at the humerus 

 and connecting almost at right angles with a similar spot in the middle of the 

 pleura. Abdomen black, with two greenish-yellow or yellow spots and two cross- 

 bands ; the spots (on the second segment) are large, oval and in contact with the 

 lateral margin; the cross-bands (on segments 3 and 4) have a triangular notch 

 or excision on their hind margin (in some specimens they are altogetlier inter- 

 rupted); on each side of the notch they are convex, so as to come in contact 

 with the abdominal margin with less than their greatest breadth; hind mar- 

 gin of the fourth segment margined with yellow. Venter black, segments 



2, 3, 4, each, with a broad yellow cross-band at the base, coarctate in the mid- 

 dle. Legs yellow; proximal half of the four anterior femora black; hind 

 femora black, except at tip; hind tibiae with a brown ring in the middle, 

 sometimes expanding'over the whole tibia; tarsi more or less brmvn. Wings 

 with a distinct grayish tinge, stigma brownish; the hind vein forms a distinct 

 sinus, encroaching upon the first posterior cell. 



Male. — The white spots on the pleurae are less perceptible ; the cross-bands 

 are sometimes interrupted in the middle, especially in the smaller specimens. 

 In one of the specimens the spots on the second segment, as well as the inter- 

 rupted cross-bands are separated from the lateral margin by a distinct black 

 interval. 



Habitat, Lalie Superior (collect. A. Agussiz) ; Xorway, Me. (S. 

 I. Smith); Mt. Washington, Alpine region (G. Dimmock). The 

 largest lot I received from Mr. H. K. Morrison, who collected it in 

 the White Mountains. Altogether I had fourteen males and au 

 equal number of females. 



The cross-bands and spots on the abdomen usually are greenish, 

 like those of the European D. alneti; sometimes, however, they 

 are yellow. 



D. laxa differs from D. fucipes Loew in the shape of the abdom- 

 inal cross-bands, which in the latter, become broader on each side, 

 but do not reach the margin ; also in the color of the femora, etc. 



As D.fascipes Leow is the American representative of the Euro- 

 pean B.fasciaia, D. laxa represents Didca alneti. 



