374 C R. OSTEN SACKEN'S PRODROME 



the latter specimen, the venter is ahnost entirely yellow, except at the extreme tip ; in very 

 dark specimens it is almost entirely black. The pattern of the wings is remarkably uni- 

 form in all specimens. 



Male. Body altogether black ; abdomen, towards the tip with grayish golden hairs, 

 which, on the second, third, and fourth segments, form faint triangles; (in rubbed off 

 specimens a very faint gray triangle is visible on the second segment). Venter black, some- 

 times brownish on the sides of the posterior margins of the segments, clothed with golden 

 hairs, especially on the margins. The thorax is clothed with black hairs ; in some speci- 

 mens, however, rather numerous yellowish-gray hairs are mixed with them, in which case 

 the thorax somewhat resembles that of the female ; a trace of gray pollen is visible anteri- 

 orly. The pattern of the wings is like that of the female, only the brown of the two basal 

 cells is more intense and reaches beyond the middle of the cells, reaching the brown in the 

 proximal end of the fifth posterior cell, thus leaving a well-marked hyaline fenestrate spot 

 in the shape of a parallelogram in the middle of the wing. The In-ownish tinge in the anal 

 cell and in the anal angle is also more saturate than in the female. A slight blackish 

 shadow (indistinct in some specimens), is visible in the hyaline -portion of the marginal cell, 

 near the costa (a mere vestige of it is often perceptible in female specimens). 



Hah. A common and wide-spread species. Catskill, N. Y., in July; Waterville, N. H., 

 July (Scudder) ; different parts of British America (the same) ; Lake Superior (A. Agassiz); 

 Yukon River and MacKeuzie River (Kennicott) ; Anticosti (Verrill), etc. Twenty-five fe- 

 male and five male specimens. 



Observation. The description was principally drawn from eight well preserved and fresh 

 Bpecimens, male and female, which I caught in the summer of 1874 near the Mountain 

 House, Catskill, N. Y. The specimens from Anticosti are very dark, and the flicial pollen is 

 o-ravish, rather than fulvous. I have but little doubt concerning the identity of the above 

 described species Avith Mr. Walker's C. excitans. Some error must have been committed 

 by him in the description of the antennee, which is not clear. He describes only the female. 



3. Chrysops mitis n. sp. 



? Chrysops provocans Walker, Dipt. Sanml., p. 73. 



?. Apex of the wings liyaline ; proximal half of tlio two basal cells infiiseateil ; anal cell and anal angle 

 more or less tino-ed with brownish; two grayisli, interrupted lines on the thorax; abdomen altogether black, 

 with faint triangles of grayish hair. 



Length, 11-12 mm. 



Not unlike the preceding species, from which the female is easily distinguished by an 

 altogether black abdomen, with a grayish and not golden pubescence. 



Female. Head as in C. excitans, only the pollen on face and front is 3'ellowish-gray, in- 

 stead of fidvous ; (in one of my specimens, however, it is fidvous). zVntenna) black, first 

 ioint reddish, black at tip ; second, blackish-red on the underside. Thoracic dorsum with 

 two gray longitudinal lines, reaching to about the middle ; interval between them brownish, 

 grayish-poUinose anteriorly, where the beginning of a blackish line is visible ; pleurae with 

 dense j'ellowish-gray hairs in the upper part ; some black hahs between the root of the 

 wino-s and the hmueri. Abdomen black, with a thinly scattered grayish pubescence, more 



