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). 



cf, 9 . Arista with about six branches above and three below. Antennae 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 sLx rows; no prescutellars. Mesonotum and scutellum yellow, 

 slightly shining. Pleurae and legs pale yellow. Apical and preapical bristles on first and 

 second tibiae, 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; ox index about 1.8; 

 Ac 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. caribhea 

 Sturtevant, especially in pinned material. In life the three species can be 

 distinguished at a glance. D. caribbea is duller in color and stouter and 

 more compressed laterally than are the other two. D. willistoni is more 

 slender than D. melanogaster, and has much less distinct abdominal bands. 

 In pinned material the three species may be recognized, as follows: 



1. Acrostichal hairs in six rows willistoni 



Acrostichal hairs in eight rows 2 



2. Costal index about 2.1; combs on male front tarsi melanogaster 



Costal index about 1.5; no combs on tarsi 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- 



Exot., 2, 3, 259). 

 D. ampelophila Loew. 1862. Berlin ent. Zeit., 6, 231. 

 D. uvarum Rondani. 1875. Bull. Com. agr. Farm. 



cT. Arista with about five branches above and three below. Antennae 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. 



