Description of Characters. 15 



Yellow (y). (Plate 1, Figure 2.) 



Description.— YqWow changes the ground-color of the entire fly from dark brown 

 to yellow (compare figs. 1 and 2, plate 1). The change is especially noticeable in the 

 wings, although it is readily observable in body and legs, especially in young flics. 

 Very old flies are darkened, so that the body-color approaches that of pale specimens 

 of non-yellow stocks. The color of the hairs and bristles in yellow flics is not notice- 

 ably different from normal. They may be faintly tinged with bronze, but if so the 

 change is very slight. Yellow averages slightly later than normal flies in hatching, 

 and has somewhat lowered viability. 



Origin. — (1281, 2127.) Several males appeared in a mass culture. (See Metz. 

 1916d, p. 599.) 



Comparison. — Yellow resembles the "yellow" of D. melanogaster, D. simnlanB, 

 D. willistoni, and D. obscura, except for its brown instead of bronze or yellow bristles 

 and hairs.* In each of these species the character is sex-linked, and it is possible that 

 they are all homologous. 



Frayed (fd). 



Description. — In frayed flies the dorsal bands of the pigment on the abdomen are 

 frayed out or irregularly broken at the ends as they extend down the sides of the 

 body. Accompanying this are various other modifications. Almost the entire fly is 

 affected in some way (see figs. 3 and 6, Metz, 1918); the thoracic bristles are reduced 

 to little more than hairs; some of the bristles on the head are entirely gone; frequently 

 the aristae, and sometimes the entire antennae, are abortive or wanting; the wings are 

 frequently broken and disarranged in various ways; and finally, development is 

 retarded several days, so that frayed flies hatch several days later than normal. 

 Frayed is recessive to wild-type. The stock was lost soon after the character first 

 appeared, owing to the sterility of the females. 



Origin. — (V 590.) Several males appeared in a mass culture (see Metz, 1918, 

 p. 110). 



Crossveinless (c). (Plate 1, Figure 2.) 



Description. — This character is distinguished by the absence of the posterior 

 cross-vein and sometimes part or all of the anterior cross-vein. 



Origin. — (See Weinstein, 1920.) 



Comparison. — Crossveinless resembles the crossveinless of D. melanogaster and 

 non-sex-linked characters of the same general type in D. obscura and D. willistoni 

 (unpublished data). 



Vermilion (v). (Plate 1, Figure 5.) 



Description. — Vermilion, like sepia, is an eye-color character. The color is near 

 Ridgeway's scarlet, but slightly darker and more yellowish. Vermilion is also char- 

 acterized by the presence of the dark fleck in the eye, which is absent in the other 

 stocks of virilis. It bears a close resemblance to the eye-color of the wild type D. 

 melanogaster, with perhaps a darker tinge. It can be distinguished from normal in 

 flies of any age. 



Origin. — (E 1.) One male was found in a stock bottle. 



Comparison. — In appearance vermilion suggests the characters of the same name 

 in D. melanogaster, obscura, and willistoni (unpublished data of Miss Ruth Ferry), 

 although the actual color is considerably darker than in these sj)ecies. 



Vesiculated (vs). (Plate 2, Figure 2.) 



Description. — Vesiculated is characterized by the presence of vesicles or blisters 

 in the wings. Occasionally the entire wing may be swollen into a single large vesicle 



'In the latter respect it suggests "lemon" in D. melanogaster (Morg.in and Bridgei, 1916). 

 In lemon, however, the males are infertile and have low viability, and the females are unknown- 



