SCELLUS. 207 



dust, marked with a few spots of whitish dust. Its lateral stripes 

 are covered with brown, the edge of the lateral margin, however, 

 again with gray-whitish dust. The abdomen is more green, less 

 coppery and less bright than in the male. The dust upon the 

 pleurae and upon the fore coxae is less yellow. The fore femora 

 are of a similar structure as those of the male ; the fore tibiae with- 

 out a thorn on the inside, elongated at the tip in a much smaller 

 and sharper tooth, before which there is no excision ; otherwise 

 the feet are plain, the middle and hind femora straight and much 

 more slender than in the male ; middle and hind tibiae only sparely 

 beset with scattered bristles. 



Observation. As I do not possess a North American female 

 of &. spinipes, I have prepared the above description from 

 Swedish specimens. 



3. S. avidws, nov. sp. . Thoracis dorso seneo-nigro, nitido, mar- 

 giiie et linea media cinereo-pollinosis, pleurarum plaga supera, abdo- 

 mineque ex viridi laete cupreis, nitidissimis, halteribus albis, alis cine- 

 reis, punctis duobus nigris, altero in vena transversa posteriore, altero 

 in ultimo venae longitudinalis quartse segmento ; lamellis analibus maris 

 albis, basi et apice tamen nigris. 



Upper side of the thorax bronze-black, shining, its margin and a middle 

 line dusted with gray powder ; a large spot on the upper part of the 

 pleurae and the abdomen bright greenish copper-colored, very shining ; 

 halteres white ; wings gray with two large dots, one on the posterior 

 transverse vein, the other upon the last segment of the fourth longitu- 

 dinal vein ; the anal appendages of the male are white, but their basis 

 and tip are black. Long. corp. 0.17. Long. al. 0.21. 



Male. Face somewhat broader than in the previous two spe- 

 cies, dusted with bright ochre-yellow powder, opaque. Front 

 with white dust. Antennae black. Most of the upper side of the 

 thorax bright bronze-black with faint violet reflections ; its whole 

 margin has a rather broad border dusted -with a whitish-gray pow- 

 der, and therefore opaque ; there is also a narrow middle line, 

 which is much abbreviated behind and likewise dusted with a 

 white-grayish powder. The upper part of the pleurae, from the 

 shoulder to the root of the- wings, is entirely without dust, metallic 

 greenish copper-colored, very much shining ; as I have only a sin- 

 gle specimen, I am unable to judge with certainty whether this 

 large shining spot is also present in fresh specimens, as I believe 

 it to be, or whether in the above described specimen it is merely 



