Sept-Dec, I9i8.] VaN DykE : REVIEW OF GeNUS SilIS. 167 



In the original descriptions, the two spiny projections of the 

 process were given as the anterior and posterior angles of the in- 

 cisure, hence have misled those dependent upon them for their 

 determination. I have therefore thought it best to redescribe it. Of 

 the first, spinigcra, I have seen besides the type from Oregon, speci- 

 mens from the following localities in the Sierras of California, Lake 

 Tahoe, Tuolumne Co., Mariposa Co., Fresno Co., and Tulare Co. ; 

 and of the second, miinita, besides the type from Atlanta, Idaho, 

 specimens from Lake Tahoe and the high Southern Sierras of Tulare 

 Co., Cal., as well as from Utah and from Garland, Col. 



Silis difficilis Lee. 



Silis difficilis Lee, Agassiz, L. Superior (1850), p. 230; Trans. Amer. Ent. 



Soc, Vol. V (1874), p. 60; Trans. Amer. Ent. Soc, Vol. IX (1881), 



P- 57. 

 Silis flavida Lee., Trans. Amer. Ent. Soc., Vol. V (1874), p. 61; Trans. 



Amer. Ent. Soc, Vol. IX (1881), p. 57. 



After critically examining a large series of the two forms given 

 above, I have finally come to the conclusion that they are only phases 

 of one species. The first, difficilis, is black with the disc of the pro- 

 thorax an orange red, and is to be found not only in the Lake Supe- 

 rior region but farther north into the old Hudson Bay Territory, 

 south through the Rocky Mountains of Colorado and into New 

 Mexico and northern Arizona, west into British Columbia, the North- 

 ern Cascades of Washington, and as a stray in the Southern Sierras 

 of California, probably overlapping from Arizona. The Lake Supe- 

 rior and more northern specimens are apt to be slightly smaller, with 

 prothorax less laterally expanded, the antennae more filiform, and the 

 elytra more scabrous than those of the Rockies and Cascade-Sierra 

 ranges, though they grade into each other. Flavida is the light 

 phase, found in the Northern Cascades and the high Sierras. On 

 Mt. Ranier, Washington, I found it in company with the preceding 

 phase, but in the major part of the Sierras it is found alone. In 

 some of the specimens, the prothorax is apparently less broad and 

 with the anterior angles of the incisure more obtuse than in typical 

 specimens. Some specimens are also more densely pilose than others. 

 In the LeConte collection the first specimen of difficilis, the one with 

 the label, cannot be the type as it bears a New Mexico locality label. 

 It was described as from the Lake Superior region. Specimen No. 

 2 is presumably the type. (Plate IX, fig. 3.) 



