NOTES ON NORTH AMERICAN THYSANOPTERA 21 



rounded to base of tube. Tube about three-fourths as long as head, 

 twice as wide at base as at apex, sides straight. Abdominal bristles long, 

 pointed ; terminal bristles brown, the longest about equal in length to 

 tube ; all other bristles yellow. 



Measurements of holotype {forma macroptera) : Length 2.12 mm.; 

 head, length 0.278 mm., width 0.232 mm.; prothorax, length 0.192 

 mm., width (inclusive of coxae) 0.426 mm. ; pterothorax, width 0.482 

 mm.; abdomen, width 0.540 mm.; tube, length 0.222 mm., width at 

 base 0.084 mm., at apex 0.047 mm. Antennal segments: 1, exposed 

 length Alfi, complete length about 60/< ; 2, 72/i ; 3, 93^; 4, 87/^; 

 5, 76/<; 6, 69/(; 7, 62/x; 8, 5Ij«; total length of antenna 0.55 mm., 

 width at segment 3, 0.038 mm. 



Female {forma brachyptera) : Closely resembling the long-winged 

 form. Eyes smaller, about one-fourth as long as head ; prothorax larger, 

 about three-fourths as long as head ; pterothorax usually equal in width 

 to prothorax. 



Male {forma macroptera) : Length about 1 .8 mm. Color and gen- 

 eral structure nearly as in macropterous female. Prothorax about 0.9 as 

 long as head ; fore femora usually greatly enlarged, attaining or slightly 

 surpassing posterior margins of eyes ; fore tarsus with a stout tooth two- 

 thirds as long as eye. Abdomen less stout and more tapering than in 

 female. 



Measurements of allotype {forma macroptera) : Length 1 .88 mm. ; 

 head, length 0.280 mm., width 0.2 1 mm. ; prothorax, length 0.232 

 mm., width (inclusive of coxae) 0.444 mm. ; pterothorax, width 0.492 

 mm. ; abdomen, width 0.5 1 6 mm. ; tube, length 0.204 mm., width at 

 base 0.078 mm., at apex 0.042 mm. Antennal segments: 1, 48/i; 

 2, 67//; 3, 87/i; 4, 84/<; 5, 75/i; 6, 65/i; 7, 54/i; 8, 46/t; total 

 length of antenna, 0.53 mm., width at segment 3, 0.034 mm. 



Male {forma hrachyptera) : Closely resembling the long-winged form 

 of this sex. Prothorcix fully as long a& the head ; fore femora often 

 greatly enlaurged, sometimes nearly as wide as head and almost attaining 

 anterior margins of eyes. 



Described from 33 females and 17 males, as follows: Plummer's 

 Island, Maryland, May 18, 1 9 1 3, J. D. H., in burrows of Elaphidion 

 sp., immediately under bark of dead hickory twig, 10 macropterous 

 females, 1 3 brachypterous females, 3 macropterous males, and 9 bra- 

 chypterous males; Plummer's Island, Maryland, October 12, 1913, 



