36 BULLETIX 826, U. S. DEPARTMENT OF AGRICULTURE. 
Drepanosiphina, this development varies to a great extent in the 
different species. 
Only two genera occur in the tribe. They may he separated as 
follows : 
Key to the Gexeea of the Pteeocommixa. 
Cornicles cylindrical Pterocomma. 
Cornicles somewhat swollen Melanoxar»therium 
Genus PTEROCOMMA Bucktoa. 
Plate !V, PP. 
1857. Cladobius Koch, Die Pflanzenlause Aphiden, p. 251. 
1860. Aphioides Passeiini, Gli Afidi, p. 28. 
1879. Pterocomma Buckton, Monog. Br. Aphides, v. 2, p. 142. 
1905. A ristaphis Kirkaldy, Can. Ent., v. 37, p. 416. 
In 1857 Koch erected the genus Cladobius with populeus Kalt. as 
type. This name, however, had been used previously. So Passerini 
in I860 employed the name Aphioides. This name had also been 
used. Kirkaldy, therefore, gave the new name Aristaphis in 1905. 
In 1879, however, Buckton described the genus Pterocomma with a 
very similar species as type. 
Characters. — Cornicles present, rather short and cylindrical. Antennae oi six 
segments armed with prominent hairs and sub circular sensoria. Fore wings with the 
media twice branched; hind wings with both media and cubitus present. Cauda 
and anal plate rounded. 
Type (mono typical), Pterocomma pilosa Buekt. 
Genus MELANOXANTEERIUM Schouteden. 
Plate IV. XX, 00. 
1879. MelanoxantJius Buckton, Monog. Br. Aphides, v. 2, p. 21. 
1901. Melanozaniherium Schouteden, Ann. Ent. Soc. Belg., v. 45, p. 113. 
In 1879 Buckton described the genus Melanoxanthus with solids 
L. as type, but, as this name was preoccupied, Schouteden suggested 
the name Melanoxantherium. 
Characters. — Cornicles present, variable in size, but usually more or less swollen. 
Antennae of six segments armed thickly with hairs and possessing oval or sub circular 
sensoria. Fore wings with the media twice branched, hind wings with both media 
and cubitus present. Cauda and anal plate rounded. 
Forms living in colonies usually on the bark of trees, males usually winged. Ovi- 
parous females laying several eggs. 
Type (monotypical). Aphis salicis L. 1 
Subtribe FULLAWAYINA. 
The subtribe Fullawayina is related somewhat closely to the 
Chaitophorina from which it is a specialization, as is evidenced by the 
reduction and total lack of the cornicles. It is very suggestive of 
Monaphis, but evidently arose from quite a different line of develop- 
ment, following Chaitophorus rather than the Callipterus group. 
Only one genus is represented. 
1 The writer is forced to change Ms view that Pterocomma pilosa is closely related to 'populifoliac 
Fitch. This was based on Pergande's published statement of his examination of the type. Later notes 
on the type indicated that it resembles popitfea. 
