228 THE AMERICAN NATURALIST [Vol. LYI 



over the abdomen as if the margins were constricted 

 (Fig. 8). The depression between the scutellum and 

 thorax of normal flies is eradicated, leaving a smooth 

 surface at the junction. The thick marginal rim of hairs 

 is the most constant of the effects of rimmed, but the 

 other changes are usually apparent. 



Origin. — Several males were found in wild type stock. 



Pale {pa) 



Description. — .The post-vertical and all the thoracic 

 bristles are pale yellow. Occasionally, a few other head 

 bristles are also yellow. The bristles are thin, and the 

 entire fly is weak and small with the wings often not un- 

 folded. None of the original pale flies could be induced 

 to breed. The heterozygous females produced a few 

 pale offspring, but the stock was soon lost. 



Origin. — The mother of the culture in which pale ap- 

 peared was heterozygous for scute rimmed on one X- 

 chromosome and for pale morula on the other. Five sis- 

 ters of this female were bred, but no pale offspring were 

 obtained from any of them. It is impossible to tell 

 whether the mutation to pale occurred in the mother of 

 the culture in which pale was found or whether it took 

 place in her mother. 



Stump (s) 



Description. — The distal portion of the second vein is 

 lacking, leaving only a stump at the base of the wing 

 (Fig. 12). This stump varies in length from one quar- 

 ter to two thirds that of the normal vein. 



Origin. — Six stump males were obtained from a mass 

 culture in which the mothers were heterozygous for 

 forked and the fathers were normal. Four of the stump 

 males were also forked, the others were not. 



The Short Allelomorphic Series 

 1. Short (sh) 



Description. — Typically, all the veins of the wing 

 fail to reach the margin in short flies, although 



