ee ce 
Vinegar-fly (Drosophila funebris). 287 
agrees very closely with that of the blow-fly larva.* Slight 
differences in the shape of the sclerites are noticeable, 
particularly in the parastomial sclerites, which in Droso- 
phila join together in front, and form a conspicuous knob 
to which muscles are attached (fig. 2). 
Alimentary Canal.—The alimentary canal exhibits the 
same parts and the same general structure as that of the 
blow-fly larva.t The anterior part is shown in fig. 2. 
The pharynx exhibits a well-developed straining appar- 
atus. It is more perfect in Drosophila than in the blow- 
fly, and approaches more closely to the arrangement found 
in the Eristalis larva, as described by J. J. Wilkinson, 
though it is not so large or efficient (fig. 3). 
, Ay 
ex 
SRT MM) VI AW! 
\\ w us 
alti As (Au 
2 Hires 2: 
Anterior segments of a late larva viewed as a transparent object. (x 50.) a.c., 
anterior connective ; a.sp., anterior spiracle; oes., cesophagus; ph., pharynx with 
straining appendage ; pr., proventriculus ; s.g., s.d., salivary gland and duct ; ¢r., main 
tracheal trunk of left side ; v.co., ventral complex. 
“The floor of the strainer bears nine parallel longi- 
tudinal ribs which are probably folds of the chitinous 
lining. They are long, narrow and deep, resembling 
planks set on their edges at equal distances. In front 
they begin abruptly, their lower-ends lying in one trans- 
verse line, and they are continued to the hinder-end of 
the chamber. While their lower-edges are attached to 
the floor, their upper-edges are free and bear fringes of 
numerous close-set barbules. The outermost rib on each 
side has only a single fringe, which projects inwards; 
* Lowne (1890-95), pp. 37-46. Lowne (1890-95), pp. 55-62. 
