SYSTEMATIC ACCOUNT. 89 
The chromosomes have been described by Metz (1916, Amer. Nat., 
50; see p. 39 of this paper). The mating habits are described elsewhere in 
this paper (see p. 6). 
Drosophila willistoni Sturtevant. 1916. Ann. Ent. Soc. America, 9, 327. 
D. pallida Williston. 1896. Trans. Ent. Soc. London, p. 415 (not Zetterstedt. 1847. 
Dipt. Scand., 6). 
3, 2. Arista with about six branches above and three below. Antenne yellow. 
Front over one-third width of head, wider above; yellow. Second orbital about one-third 
other two. Second oral bristle nearly as long as first. Carina flat, not nose-like; face yel- 
low. Cheeks yellow; their greatest width about one-eighth greatest diameter of eyes. 
Eyes distinctly pilose. 
Acrostichal hairs in six rows; no prescutellars. Mesonotum and scutellum yellow, 
slightly shining. Pleure and legs pale yellow. Apical and preapical bristles on first and 
second tibie, preapicals on third. 
Abdomen yellow, each segment with a dark-brown posterior margin. 
Wings clear. Costal index about 1.8; fourth-vein index about 2.1; 5x index about 1.8; 
4c index about 1.4. 
Length body 1.8 mm.; wing 1.8 mm. 
Specimens examined: Miami, Florida; Nassau, Bahamas (A. Busck); 
Herradura (C. W. Metz), Havana, Santiago de las Vegas, Guantanamo 
(C. W. Metz, C. T. Ramsden), Cuba; Haiti (coll. A. L. Melander); Porus, 
Jamaica (C. W. Metz); Bayamon (A. Busck), Mayaguez (Hooker), Porto 
Rico; St. Vincent (Williston type material); San Jose, Port Limon, Costa 
Rica; Panama, Republic of Panama; Manaos, Brazil (Miss H. B. Merrill). 
Adams (1905, Kans. Univ. Sci. Bull., 3) has reported the species from 
Rhodesia, South Africa. In view of the large number of known species 
similar in appearance to this one, a record from the Ethiopian region is 
doubtful unless very carefully checked up. 
This species is very similar to D. melanogaster Meigen and to D. caribbea 
Sturtevant, especially in pinned material. In life the three species can be 
distinguished at a glance. JD. caribbea is duller in color and stouter and 
more compressed laterally than are the other two. D. willistont is more 
slender than D. melanogaster, and has much less distinct abdominal bands. 
In pinned material the three species may be recognized, as follows: 
Heme CEOSUM Nel MATS IIR BURVTOWE ionic 1h saci! cb els iu lc gcudear ees uidialabe mlp)lc ele Niall nabeabare willistont 
PECLONSGLC Hey DEAT UIA CLEP TOTS eos (cs 8 io sind asada doo a peiene Ahk Ui sochas ain a cisates ele ey otavers 2 
2. Costal index about 2.1; combs on male front tarsi.................-.+.- melanogaster 
Costal mdex about 1250 combs on tared 9530-4 ob) eos ie caribbea 
This species is very common about fruit in the tropics. I have bred it 
from banana, grape-fruit, papaya, and pineapple. It is easily kept for 
many generations in the laboratory, banana serving as a convenient food. 
About two weeks are required for its development. 
The chromosomes have been described by Metz (1916, Amer. Nat., 50; 
see p. 39 of this paper). The mating habits are described on page 7. 
Drosophila melanogaster Meigen. 1830. Syst. Beschr., 6,85. (Plate 3, fig. 2.) 
D. nigriventris Zetterstedt. 1847. Dipt. Scand., 6, 2557. (Not Macquart. 1843. Dipt- 
IXOtes 2. apeoo). : 
D. ampelophila Loew. 1862. Berlin ent. Zeit., 6, 231. 
D. uvarum Rondani. 1875. Bull. Com. agr. Parm. 
o'. Arista with about five branches above and three below. Antenne yellow. Front 
nearly one-half width of head, wider above; yellow. Second orbital one-third size of other 
two. Second oral bristle nearly as long as first. Carina rather broad, flat; face yellow. 
Cheeks yellow; their greatest width about one-fifth greatest diameter of eyes. Eyes with 
rather thick pile. 
