34 MISCELLANEOUS STUDIES 



Although the anal plate is somewhat notched, there is scarcely 

 difference enough to warrant the forming of a new genus. In fact, 

 in many specimens one cannot tell whether or not a notch is present. 

 As to the cauda, consisting of the tip, a distinct neck, and a distinctly 

 conical base, this is not greatly different from a cauda consisting of 

 a knobbed tip on a quadrangular base. The only practical difference 

 is in the base, being conical in one and quadrangular in the other. In 

 populifolii (Essig) the base seems to be conical, yet one cannot be 

 certain unless the specimen is mounted exactly. 



This species, A. populifolii (Essig), as stated above, was described 

 from specimens taken on Popuhis trichocarpa at Santa Paula. In 

 1910 Davidson found a species on Populus fremonti at Stanford Uni- 

 versity, and the following year at Penryn, Placer County, which he 

 listed as Chaitophorus populifoliae (Fitch). A careful study of 

 specimens from Davidson and the cotypes of Essig 's species convinced 

 the author that they were identical. Morrison writes that Davidson's 

 specimens are not C. populifoliae (Fitch), so Essig 's species is distinct. 

 In September, 1915, the author observed a great number of specimens 

 of this species on a weeping elm (TJlmus sp.) in Berkeley, which was 

 in close proximity to some populars. However, none were seen to be 

 feeding on the elm, all being restless and wandering over the leaves 

 and branches. In southern California this is often found infesting 

 the empty galls of Thecabms populimonilis Riley, such having been 

 observed in San Diego and Riverside counties. 



29. Arctaphis viminalis (Monell) ? 



Monell, U. S. Geol. Geog. Surv., Bull. 5, p. 31, 1879. Callipterus (orig. 



desc.). 



Clarke, Can. Ent., vol. 35, p. 248, 1903. Chaitophorus (list). 

 Davidson, Jour. Econ. Ent., vol. 3, p. 375, 1910. Chaitophorus (list). 

 Davidson, Pom. Jour. Ent., vol. 3, p. 398, 1911. Chaitophorus (list). 

 Essig, Pom. Jour. Ent., vol. 4, p. 716, 1912. Thomasia (list, key to Califor- 



nian species of Thomasia). 

 Patch, Maine Agr. Exp. Sta., Bull. 213, p. 80, 1913. CJiaitophorus (desc.). 



Records Salix spp. ; Watsonville, Santa Cruz County, and Newcastle, Placer 

 County (Clarke); Penryn, Placer County, and Stanford University (Davidson). 



This species has been reported from Placer, Santa Clara, and 

 Santa Cruz counties on various species of willow. The true Chai- 

 tophorus viminalis Monell is an Arctaphis, but whether or not the 

 western species is the same as the eastern is a question. The author 

 has never seen specimens of either and is therefore unable to make 



