SARCOPHAGID.E. 15 



lateral plates. From their base, near the origin of the hypostomals, 

 there j)rojects forward and upward a pair of slender })ieces, the 

 parastomal sclerites. The shape and proportion of these parts vaiy 

 with the different species and are quite different in the newly-hatched 

 larva than in the full-grown maggot. 



The anterior spiracles do not appear on the larva while in its first 

 stage, but usually appear in the second stage, although sometimes 

 deferred till the third or full-grown stage. 



The posterior stigmal plates in the larvae of the first stage are quite 

 small and generally have a simple heart-shaped apeitiu-e; in the 

 second stage, the plates become more elongate and each has two short 

 slits. In the third stage, there are alwaj^^s three slits of varying shapes 

 according to the species. 



The number of segments in the body of a larva is a disputed ques- 

 tion. Apparently there are 12; with the hidden Newport's segment, 

 this would make 13, a number accepted by several investigators. 

 Others, however, claim there are really 14 or 15 segments. 



SYNOPSIS OF THE GROUPS. 



1. Body with lateral and dorsal spinose processes Homalomyia. 



Body without such processes 2 



2. Body ending in two fleshy processes; rather small species 3 



Body truncate or broadly rounded at end 4 



3. Processes bearing the stigmal plates; body about 5 mm. long Drosophila 



Processes not bearing the stigmal plates; body 10 mm. in length or longer. . I'iophila. 



4. But one great hook; posterior stigmal plates with winding slits; no distinct lateral 



fusiform areas; tip of body with few if any conical processes Muscinse. 



With two great hooks; slits in the stigmal plate not sinuous 5 



5. No tubercles above anal area; no distinct processes around stigmal field 6 



Distinct tubercles above anal area; often processes around stigmal field; lateral 



fusiform areas usually distinct 7 



6. Stigmal plates on black tubercles; lateral fusiform areas distinct Ortalidse. 



Stigmal plates l)arely if at all elevated; lateral fusiform areas indistinct; stigmal 



plates often contiguous or nearly so; slits long and subparallel Trypetidse. 



7. Slits in stigmal plates rather short, and arranged radiately 8 



Slits slender, and subparallel to each other 9 



8. Two tubercles above anal area; stigmal field with distinct processes around it. 



Anthomyiidse. 



Four or more tubercles above anal area; slits of stigmal plates usually pointed at 



one end Miiscina. 



9. A button to each stigmal plate; slits rather transverse to body (,'alliphorinae. 



No button to stigmal plates, slits of one plate subparallel to those in opposite plate; 



plates at bottom of a pit Sarcophagidoe. 



SARCOPHAGID^. 



In the Sarcophagidffi the hooks are two in number and the posterior 

 stigmal plates have three straight slits as in the Callii)liorina\ How- 

 ever, these slits are not directed toward those of the opposite plate 

 10039°— No. 22—12 3 



