SYSTEMATIC ACCOUNT. 93 



Specimens examined: Herradura (C. W. Metz), Havana (type material), 

 Santiago de las Vegas, Baracoa (U. S. Nat. Mus.), Santiago de Cuba (C. W. 

 Metz), Guantanamo (C. T. Ramsden, F. E. Lutz), Cuba; Sanchez, Haiti 

 (F. E. Watson); Mayaguez, Porto Rico (F. E. Lutz); Antigua (H. A. 

 Ballou) ; Roseau, Dominica (F. E. Lutz) ; Punta Gorda, British Honduras 

 (U. S. Nat. Mus.); San Jose, Costa Rica; Taboga Island (A. Busck), 

 Panama, Republic of Panama; Manaos, Brazil (Miss H. B. Merrill). 



This species is quite common about fruit in Cuba and Central America. 

 As I have pointed out elsewhere (1918, Journ. Parasitology, 5, 84), it is 

 rather frequent about human excrement, and sometimes breeds on it. 

 I have seen specimens bred from the feces of a dysentery patient in Cuba 

 by Mr. J. R. Taylor. I have myself bred the species from banana, guava, 

 marinon, orange, papaya, pineapple, plantain, and zapote. About twelve 

 days are required for its development. It can be bred in the laboratory 

 through many generations with comparative ease, banana being a satis- 

 factory food for this purpose. 



The eggs have two filaments. An account of the chromosomes, of the 

 mating habits, and of a mutation found in this species will be found else- 

 where in this paper. 



Group F. 



Typical species. Subgroup 2: Blackish or grayish species. 

 Drosophila obscura Fallen. 1823. Dipt. Suec. Geomyz., 6, 6. 



D. tristis Meigen. 1830. Syst. Beschr. (not Fallen. 1823. Dipt. Suec). 

 cf. Arista with about four branches above and two below. Antennse brown, third 

 joint dark. Front over one-third width of head, wider above; opaque brown, orbits and 

 ocellar triangle gray pollinose. Second orbital one-half other two. Second oral bristle 

 about one-half size of first. Carina broad, high; face dark brown. Cheeks grayish brown, 

 their greatest width about one-sixth greatest diameter of eyes. Eyes with rather thick pile. 



Fig. 47. — Drosophila obscura. Front leg of male, showing two tarsal combs. 



Acrostichal hairs in eight rows; no prescutellars. Mesonotum, scutellum, and pleurae 

 dark dull grayish-brown, mesonotum sometimes slightly grayish polUnose. Legs pale 

 brown, femora darker. There is a small comb of short, stout, curved black bristles on the 

 inner side of each of the two basal joints of each front tarsus (fig. 47). Apical and preapical 

 bristles on first and second tibiae, preapicals on third. 



Abdomen dark blackish-brown, somewhat shining toward the apex. 



Wings clear, veins brown. Costal index about 2.7; fourth-vein index about 1.9; 5x 

 index about 1.5; 4c index about 0.9. 



Length of body 2.2 mm.; wing 2.3 mm. 



9 . Agree, only no tarsal combs. In life show anterior pale bands on each abdominal 

 segment. 



Specimens examined: Italy (det. Bezzi); Holland (det. J. C. H. de 

 Meijere); Corvallis (G. F. Sykes), Amity (D. E. Lancefield), Oregon; 

 Berkeley (E. B. Babcock), Claremont (L. L. Gardner), Newport (C. W. 

 Metz), California. The species is recorded in Europe from the Canary 

 Islands to Sweden, Austria, and Italy. Coquillett (1899, Proc. U. S. Nat. 

 Mus., 21, 301) recorded it from Japan, but an examination of his specimens 

 has convinced me that they represent a different species of Drosophila. 



