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. Antennae brown, third 

 joint nearly black. Front nearly one-half width of head, wider above; dark brown, hghter 

 below, orbits and triangle polhnose. 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 graj'ish 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 pleurae 

 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 tibiae, preapicals 

 on third. 



Abdomen dark brown, lighter toward the base. 



Wings clear. Costal index about 3.6; fourth-vein index about 2.6; 5a; index about 2.0; 

 4c index about 1.2. 



Length body 2 mm.; wing 2.2 mm. 



9 . As above, except that no tarsal combs are present. In life they have j^ellow 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. Duncan); 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. S. Barber); Douglas Count}'", 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 L3. 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. 



cf . Arista with about five branches above and three below. Antennae brown. Front 

 about one-third width of head, wider above; brownish red. Second orbital scarcely more 



