38 



Linkage Group III. 



Origin. — (P 577.) One female was found in a bottle of droop stock. 



Comparison. — Spread resembles the third-chromosome recessive "spread" in D. 

 melanogaster (Dexter, 1914) and also the second-chromosome recessive "spread" in 

 D. simulans (Sturtevant, 19216, p. 186). It differs from the former in that the wings 

 are not uniformly held at an angle of 90°. In this respect it agrees more closely with 

 "spread" of simulans. 



Hunch (h), (Figure 9.) 



Description. — Hunch flies lack the usual depression between the mesonotum and 

 scutellum on the dorsal side, giving a hunch-back appearance. They frequently 

 show an exudation on each side of the thorax near the junction of mesonotum and 

 scutellum. The wings are usually soft and "moist" in texture, and sometimes are 

 only partially expanded and are held out at an acute angle from the body. 



Origin. — (L 176.) Hunch arose from a mating of a single female by two males, all 

 from the same mass culture. The offspring were 35 not-hunch and 12 hunch. Evi- 

 dently the female and at least one of the males were heterozygous for the hunch gene. 



Comparison. — Hunch agrees in its main characteristics with the third-chromosome 

 recessive "ascute" in D. melanogaster and with two similar characters in D. ohscura, 

 one sex-linked and one non-sex-linked. The latter one we have not seen, owing to 

 the stock having been lost, but Dr. Lancefield informs us that it does not differ 

 noticeably from the other. 



Fig. 9.— Hunch. 



Fig. 10. — Telescoped. 



Telescoped (t). (Figure 10.) 



Description. — Telescoped is a recessive, characterized bj' a greatly shortened or 

 telescoped thorax and a consequent close approximation of the anterior and posterior 

 pairs of dorso-central bristles. Most telescoped flies also have small, narrow eyes, or 

 in extreme cases no eyes at all, and usually the hairs on the mesonotum are sparse 

 and irregular in distribution, and the anterior dorso-central bristles are small. 



Origin. — (V 974.) A female found in confluent stock and segregated because she 

 had "groove eyes" was mated to normal-eyed males from the same bottle. Among 

 the offspring was one female \vith very narrow eyes, which, when bred to normal- 

 eyed brothers (or half brothers), gave 225 not-telescoped and 48 telescoped progeny. 

 At first the telescoped flies were distinguished merely by their narrow eyes, and it is 

 probable that among the 225 flies recorded as "not-telescoped" many telescoped were 

 present. Indeed, it is probable that the original female from confluent stock was 

 telescoped and one or more of the males to which she was mated were at least heter- 

 ozygous for telescoped. 



Comparison. — Dr. Lancefield informs us that the sex-linked character "com- 

 pressed" in D. ohscura resembled telescoped, but unfortunately the stock of com- 



