60 Comparison of Characters 



Drosophila virilis. 



Forked. — Effect moderate. Bristles erect, heavier and shorter than normal, wavy, 

 a few forked sharply at tip. Hairs on entire fly somewhat shortened but not de- 

 pressed or curled; those on arista very short, those on costa stand out at an angle of 

 about 60°. Body-color darker and glossier than normal. Both sexes fertile; eggs 

 normal. Heterozygous females have short bristles. 



Singed. — Effect extreme; probably most extreme of all the characters in the present 

 series. Bristles and hairs much like those of singed and forked-5 melanogaster, but 

 more extremely affected. Bristles, especially on scutellum, greatly depressed, short, 

 thick, twisted, curled or knotted, and forked. Hairs on body and legs depressed, 

 curled, and shortened; those on costa affected as much as in forked; those on arista 

 nearly normal, not as short as in forked. Double recessive singed-forked is like 

 singed, but has glossy body like forked. Heterozygous females have short bristles. 

 Females fertile; eggs normal. 



Drosophila willistoni. 



Stubby. — Effect slight to moderate. Bristles heavy, sharply forked, not depressed. 

 Hairs on thorax, abdomen, head, legs, and wings apparently normal; those on arista 

 apparently normal, not branched. Females fertile; eggs normal. Heterozygous 

 females not examined. 



Forked. — (From two alcoholic specimens.) Effect moderate. Bristles depressed, 

 curled, few forked. Hairs on thorax decidedly depressed, somewhat curled; those on 

 abdomen apparently same, those on legs and wings apparently slightly affected. 

 Hairs on arista long, slender, normal or nearly so, not branched. Females sterile; 

 eggs dissected from alcoholic specimen have verj' short, broad filaments, decidedly 

 abnormal, like those of singed melanogaster . Heterozygous females not examined. 



Forked-2.—{Y\om. Lancefield and Metz, 1922, p. 217.) Effect extreme. Bristles 

 twisted, thickened, forked, depressed. Hairs short, depressed, somewhat curled. 

 Hairs on arista branched. Females sterile; eggs not examined (stock lost). Heter- 

 ozygous females not examined. 



Drosophila obscura. 



Stubby.— {Yrom description, D. E. Lancefield, 1922, p. 372.) "Their main charac- 

 teristic is the shortening of the macrochaetse and a bending or twisting of the bristles 

 that occurs rather infrequently. It does not resemble the forked mutants of other 

 species." 



Singed. — Effect slight to moderate. Bristles wavy, some slightly forked at tip, 

 somewhat depressed. Hairs on thorax depressed; those on abdomen and legs not 

 depressed. Hairs on arista slightly shortened, not branched. Body glossy black; 

 females sterile; no eggs have been found, although females have been dissected and 

 attempts have been made to get them to lay eggs. It is possible that eggs do not 

 mature in singed females. Bristles of heterozygous females often shorter than normal 

 (possibly not constant). 



Drosophila simulans. 



Forked. — Effect moderate to extreme; intermediate between forked and forked-5 

 (in D. melanogaster) to which it is allelomorphic. Some hairs on arista branched, not 

 short and stubby. Females fertile, eggs normal. Resembles most closely forked 

 melanogaster. Heterozygous females apparently normal. 



Drosophila funebris. 



Forked. — Effect slight to moderate. Bristles stubby, stout, not wavy; a few forked 

 sharply near tip, not depressed. Hairs on thorax, abdomen, legs, and wings shortened, 

 but not depressed and curled as in singed virilis. Some of the bristles on abdomen 



