THE CANADIAN ENTOMOLOGIST 319 



It will be seen by these measurements that the unguis of seg- 

 ment YI is much' shorter than the base and only about one-tenth 

 as long as segment III. In the American species on the other 

 hand the base and the unguis of segment VI are almost equal, and 

 the unguis is about one-fourth as long as segment III. In the 

 American species also the anal plate is somewhat indented, whereas 

 in the European species this is not noticed. 



The apterous forms show the same differences between the 

 two species in regard to segment VI of the antenna, the European 

 species measuring III, 1.168 mm.; IV, 0.72 mm.; V, 0.512 mm.; 

 VI, (0.1-14 mm. -(-0.112 mm.). Another difference between the 

 two species in this form is that in the American species segment 

 III is armed with a row of sen'soria which cover the entire seg- 

 ment, whereas in ohlongus only the basal half of the segment is 

 covered. There is this same difference also in the alate forms, 

 but a little more than half of segment III is covered in ohlongus. 



Symydobius americanus, n. sp. 



Alate viviparous female. — ^Antennal segments asfollow^s: III, 

 0.96 mm.; IV, 0.64 mm.; V, 0.528 mm.; VI, (0.224 mm. -f 0.24 

 mm.). Segment III with a row of about 25 rather small protrud- 

 ing sensoria arranged in a more or less even row" over the entire 

 segment. Hind tibiae 1.28 mm., hind tarsus 0.192 mm.; hind wing 

 about 3 mm. long, cauda rounded, anal plate slightly notched. 



Colour brown, abdomen with dark transverse bands, cornicles 

 pale, wing veins heavily bordered with dark brow^n; antennae 

 with segments I to III and the distal extremities of IV, V and VI 

 . dark brown, the remainder yellowish white. 



Apterous viviparous female.. — Antennae as follows: III, 1.15 

 mm.; IV, 0.72 mm.; V, 0.592 mm.; VI, (0.24 mm. + 0.24 mm.). 

 Segment III, armed with about 20 circular sensoria in a some- 

 what even row' along the segment. Hind tibiae somewhat curved, 

 about 2.88 mm. long; hind tarsus 0.224 mm. Cauda and anal 

 plate similar to those of the alate form. Length from ^'ertex to 

 tip of Cauda 2.88 mm. 



Colour brown. Antennae and cornicles similar to those of the 

 alate form. Abdomen with transverse brown markings. Eyes 

 red. 



