GENERIC CLASSIFICATION OF APHIDIDAE. 41 



6. Tubercle very large, entirely covering posterior part of body; cornicles 



small, opening at the side Aspidaphis. 



Tubercle of moderate size, as large as cauda in the apterous form; cornicles 

 normal, opening at the end Cavariella. 



7. Cornicles long, very abruptly and distinctly swollen Liosomaphis. 



Cornicles of varying lengths, gradually swollen 8. 



8. Cauda short and abruptly conical; cornicles about the same length 



as cauda and swollen in the middle Brevicoryne. 



Cauda not strikingly short or abruptly conical 9. 



9. Cornicles as short as the width of cauda at base or shorter 10. 



Cornicles as long as or longer than the cauda • 11. 



10. Cornicles minute, tubercle-like Brachycolus. 



Cornicles considerably longer than their diameter; cauda, particularly 



in the apterous form, large and long Hyalopterus. 



11. Cauda in the apterous form long and broad, as long as the cornicles. .Hyadaphis. 

 Cauda shorter than the cornicles, not correspondingly long and 



broad Rhopal osiphu m . 



12. Tarsi atrophied 13. 



Tarsi normal 14. 



13. Antennae of six segments; cornicles rather short Atarsos. 



Antennae of five segments; cornicles very long and slender ^lastopoda. 



14. Cauda apparently absent, or a mere rounded piatelike structure 21. 



Cauda normal in appearance but often very short 15. 



15. Fore wings with media once branched 22. 



Fore wings with media twice branched 16. 



10. Antennae of five segments 24. 



Antennae of six segments 17. 



17. Cornicles small, as short as width of cauda at base, which is without con- 



striction 18. 



Cornicles usually as long as or longer than cauda, Aphis-like 19. 



18. Cauda very long and large in the apterous form Pergandeidia. 



Cauda extremely short and subcortical Microsiphurn. 



19. Cauda short and abruptly conical Anuraphis. 



Cauda elongate and constricted near base 20. 



20. Hind wings with media and cubitus present Aphis. 



Hind wings with only one oblique vein Hysteroneura. 



21. Cornicles minute, not as long as wide Cryptosiphum. 



Cornicles moderate in length Acaudus. 



22. Antennae of six segments Toxoptera. 



Antennae of five segments 23. 



23. Apterous form with a prominent median projection on the vertex and 



with four-segmented antennae; cornicles minute Sanbornia. 



Apterous form normal Yamataphis. 



24. Cornicles elongate, Aphis-like Cerosipha. 



Cornicles extremely short, body of apterous form, much arched . Siphonatrophia, 



Genus ACAUDUS V. d. Goot. 



Plate VI, A, B. 



1913. Acaudus Van der Goot, Tijd. voor Ent., v. 56, p. 97. 



1917. Jfacchiatiella Del Guercio, Redia, v. 12, p. 210. 



1917. Hannabwa Matsumura, Journ. Coll. Agr. Tohoku Univ., v. 7, pt. 6, p. 377. 



Van der Goot erected his genus Acaudus with lychnidis L. as type. 

 This species is quite similar to an Aphis without a cauda or with a 

 very short, somewhat rounded cauda. The cornicles are not long. 



