1916] Ferris — Notes on Anopliira and Mallophaga 107 



of small spines and a lobe-like process, which bears a single stout 

 spine, at each posterior angle. 



Pleural plates present on the second to fifth segments, rather tri- 

 angular in shape, with the posterior angles rounded and the pos- 

 terior margin slightly emarginate. Each with a pair of very small 

 spines on the posterior margin. 



Description of the male: Total length, .62 mm.; length of 

 head, .13 mm.; length of abdomen, .41 mm.; width of head, ,1 

 mm. ; width of thorax, .15 mm. ; width of abdomen, .23 mm. 



Head and thorax similar to those of the female. Abdomen, 

 however, with narrow but distinct chitinized areas on the third to 

 eighth tergites. First to third tergites with median group of four 

 to six spines, fourth to eighth with median group of six which 

 occupy the length of the chitinized area. Fourth and fifth with 

 lateral groups of two spines, sixth to eighth with lateral groups of 

 three or four. Seventh sternites without chitinized areas, the ar- 

 rangement and number of the spines being as on the dorsum, with 

 the exception of the double row on the third sternite. Pleural 

 plates as in female. 



Genitalia weakly chitinized, the parts of the mesosome being 

 very small and inconspicuous. Basal plate divided into two 

 slender parallel rods. 



Enderleinellus sphaerocephalus Nitzsch. 



Pediculus spha^rocephalus Nitzsch, Germar's Mag. f. Ent., Vol. 3, 

 p. 305 (1818); Hamatopinus spharocephalus Denny, Mon. Anopl. 

 Brit., p. 36 (1842); Polyplax (?) sphocrocephalus Dalla Torre, Gen- 

 era Insec. Anoplura, p. 14; (1908); Enderleinelhis sphocrocephalus 

 Fahrenholz, Zool. Anz., Vol. 39, p. 56 (1912). 



From Sciurus douglasi albolimbatus (Yosemite National Park, 

 Calif.), S. hudsonicus vancouverensis (Kuiu Island, Alaska) and 

 S. hudsonicus petidans (Glacier Bay, Alaska). 



The occurrence of this species upon some species of American 

 squirrels and not upon others is an interesting point in the problem 

 of the distribution of these ectoparasites. The range of Sciurus 

 griseus coincides in part with the range of S. douglasi, in fact the 

 two often live in the same trees, yet they harbor verj^ distinct 

 species of Enderleinellus. S. douglasi and S. hudsonicus, with their 

 various subspecies, certainly get no closer than the width of Behring 



