ANATOMY. 23 
hours. The final color is dark reddish-brown in Chymomyza procnemis, 
Drosophila funebris, D. immigrans, D. repleta, D. virilis, and others, 
paler and not reddish in D. melanogaster, D. obscura, D. simulans, and 
others. The posterior spiracles and ‘“‘pseudopodia” and the ventral 
hooklets (also the dorsal processes of D. busckii) of the larva are 
retained in the puparium. The anterior portion of the puparium is 
flattened, and the pupa does not extend to the end in this region. The 
cephalopharyngeal skeleton is left attached to the inner surface of the 
larval skin. The trachez coming from the anterior spiracles are broken 
off, so that they do not connect with the pupa. This is apparently 
true also of the tracheze leading from the posterior spiracles. 
The pupa itself is inclosed in a very delicate white 
membrane, which is left behind when the adult 
emerges. A few days after pupation the eyes be- 
come pinkish, and gradually deepen in color, becom- 
ing red as in the imago just before emergence. The 
legs, wings, and bristles develop in characteristic 
positions, that are occasionally retained in part after 
emergence. Familiarity with these is valuable in 
carrying out genetic experiments. A description of 
them is accordingly presented. 
The condition of the wings at the time the adult 
emerges is shown in figure 5, and needs no descrip- 
tion. 
The front femora are twisted through 360° near 
their bases. The other leg segments are straight. 
The cox all point posteriorly, the femora anteri- 
orly, and the tibie and tarsi again posteriorly. The Fic. 5.—Wing of 
legs thus lie closely and compactly against the ven- 2 newly emerged 
tral surface of the developing imago. The twist in egg ae Sagi 
the front femora is straightened at or before emerg- yet unfolded. 
ence, and is difficult to see, because it is apt to be 
lost when an old pupa is dissected unless the operation be done very 
carefully and examination made quickly. 
The bristles do not all point in the same directions as in the fully 
expanded adult fly. The anterior orbitals point forward, the two 
posterior ones backward and slightly outward, the tip of the longer 
one lying over the eye. The postverticals and inner verticals point 
inward, lying flat on the vertex. The outer verticals point outward, 
parallel to the edge of the eye. The dorsocentrals point backward and 
slightly inward, in such fashion as not to cross each other or the anterior 
scutellars. The humerals, presuturals, and anterior supra-alars point 
nearly straight backward. The anterior scutellars, postalars, posterior 
supra-alars, and posterior notopleurals point backward and inward, 
making an angle of about 45° with the dorsocentral lines. The 

