94 THE NORTH AMERICAN SPECIES OF DROSOPHILA. 
This species is a fruit-feeding form. It is easily kept in the laboratory on 
banana, and has also been bred from pineapple, orange, and tomato. About 
two weeks are required for its development. 
The eggs have two filaments. The chromosomes, mating habits, and 
certain genetic experiments are described elsewhere in this paper. 
Drosophila affinis Sturtevant. 1916. Ann. Ent. Soc. America, 9, 334. 
o. Arista with about five branches above and two below. Antenne brown, third 
joint nearly black. Front nearly one-half width of head, wider above; dark brown, lighter 
below, orbits and triangle pollinose. Second orbital three-fourths third, which is three- 
fourths first. Carina low, very narrow; face dull brown. Second oral bristle scarcely 
one-fifth first. Cheeks grayish brown; their greatest width about one-sixth greatest 
diameter of eyes. Eyes with short pile. 
Acrostichal hairs in six rows; no prescutellars. Mesonotum, scutellum, and pleure 
coffee-brown. Legs pale brownish-yellow. A comb-like row of short, stout, curved black 
bristles on the inner side of the basal tarsal joint of each front leg, as in the male of D. 
melanogaster Meigen. Apical and preapical bristles on first and second tibix, preapicals 
on third. 
Abdomen dark brown, lighter toward the base. 
Wings clear. Costal index about 3.6; fourth-vein index about 2.6; 5x index about 2.0; 
4c index about 1.2. 
Length body 2 mm.; wing 2.2 mm. 
@. As above, except that no tarsal combs are present. In life they have yellow an- 
terior bands on each abdominal segment. 
Specimens examined: Mount Washington (Mrs. Slosson), Hanover, 
New Hampshire; Beverly (Burgess), Woods Hole, Massachusetts; Niagara 
Falls (C. W. Johnson), Ithaca (E. G. Anderson), New York, Staten Island, 
New York; New Brunswick (F. E. Lutz), Fort Lee, Split Rock Pond, New 
Jersey; North Mountain, Pennsylvania (C. W. Johnson); La Fayette 
(J. M. Aldrich), Bloomington (F. Payne), North Manchester (R. R. Hyde), 
Indiana; Flat Rock, Illinois (F. N. Dunean); St. Louis, Missouri (W. V. 
Warner); Plummer’s Island, Maryland (R. C. Shannon); Washington, 
District of Columbia (R. C. Shannon); Dead Run (R. C. Shannon), Rich- 
mond, Virginia; Knoxville, Tennessee (Aldrich coll.); North Carolina 
(U. S. Nat. Mus. coll.); Greenville, South Carolina; Georgia (U. S. Nat. 
Mus. coll.); Lakeland, Florida (C. W. Metz); Kushla, Alabama; Houston 
(H. J. Muller), Willis (U. S. Nat. Mus. coll.), Texas; Wister, Oklahoma 
(H. 8. Barber); Douglas County, Kansas (coll. Univ. of Kans.). 
This species has been often identified as the European D. confusa Staeger. 
A specimen from Italy in the collection of Mr. C. W. Johnson, identified as 
D. confusa by Bezzi and agreeing with the descriptions of that species, 
differs from this form as follows: acrostichal hairs in eight rows; two 
prominent oral bristles; fourth-vein index about 1.3. I have not seen any 
American specimens that seem to me to represent this species. 
D. affinis feeds on fruit. I have bred it from banana, huckleberry, pine- 
apple, potato, watermelon, and stale beer. It is not rare about bleeding 
trees. The development takes about two weeks. 
The eggs have two filaments, slightly over one-half as long as the egg 
itself and somewhat dilated at their tips. The chromosomes have been 
described by Metz. Data on these, on the mating habits of the species, 
and on a mutation found in it by Hyde will be found elsewhere in this 
paper. 
Drosophila pseudomelanica Sturtevant. 1916. Ann. Ent. Soc. America, 9, 333. 
o’. Arista with about five branches above and three below. Antenne brown. Front 
about one-third width of head, wider above; brownish red. Second orbital scarcely more 
