no.1753. NORTH AMERICAN GEOMETRID Mollis GROSSBECK. 367 



Small, pure white dots usually surrounded by a brown border are 

 between veins R 5 to Cu, near the outer margin, though frequently 

 two or more of these are absent. In the cell between the branches of 



cubitus a black dot is situated. Discal spot white, conspicuous, 

 linear. Fringe brown. Secondaries with irregular transverse line 

 brownish followed by a whitish line which is the more prominent of 

 the two. Inner area slightly darker outwardly, the color increasing 

 in height in the outer area. Sometimes a still darker shade, becom- 

 ing intense at the anal angle, is present in the outer area extending 

 parallel and close to the cross line. On the margin near the anal 

 angle are from one to four jet black spots. Discal spol absent or 

 reflected from beneath as a very faint dusky spot. Fringe as in 

 primaries. Beneath paler than above and dusted over more or less 

 profusely with grayish or blackish atoms. Outer line of primaries 

 well marked, denticulate; discal spot white, linear, sometimes marked 

 inwardly with black. Transverse line of secondaries very sharply 

 denticulate; discal spot large, black, oval. 



Habitat. — From British Columbia southward to California and 

 eastward to Colorado. Specific localities are: British Columbia: 

 Arrowhead Lake, July 1 to August 7; Kaslo, July 15 to August 21 ; 

 Wellington, April 15. Vancouver: July 16 to 23. Washington: 

 Tacoma. Oregon: Dally. California: Cazadero, Sonoma County, 

 August 18. Utah: Stockton, July 24 to August 1; Provo, July 29 

 to August 12. Colorado: Glenwood Springs, June S to September 

 15; Chimney Gulch, Golden, June 30. 



This is the largest species of the genus and may be known by its 

 large size alone. It is a close ally to peplarioides which species also 

 approaches it most nearly in size. In giganteus the outer line of the 

 primaries is usually considerably more angulate at the veins, and the 

 male lacks the faint olivaceous tint of peplarioides. Perhaps the best 

 distinguishing feature will be found in the habitat of the two species: 

 giganteus is apparently common in British Columbia and Vancouver 

 Island, becoming more rare as the southern and eastern limits of its 

 range are approached, and may not extend south of the northern 

 third of California; peplarioides extends through New .Mexico and 

 Arizona, and is common in the southern third of ( 'alifornia. Tin- two 

 forms may fly together in middle California. The genitalia of (j'ujau- 

 teus are much like those of peplarioides; the clasper is narrower than 

 in that species and the scaphium and uncus are somew hat broader. 



This species has been generally regarded as the occidentalis of Ilulst 

 and indeed not without some justification, as Hulsl himself lias a 

 female specimen in his collection labeled as a type. This, however, 

 is from Colorado, and in his diagnosis <>f occidentalis he specifically 

 gives California as the locality from whence the species is described. 



Type- -Cut. No. 13124, U.S.N.M. 



