July — September 1SS5. 



PS en IE. 



307 



fore tlu-re c;in be I'ecognized a body 

 ( Sell rof (lev's tongue-bone) and four 

 wing-like processes which often again 

 Consist of several parts. The body is 

 connected witii the wings posteriorh . 

 It is always bent in a U-shape, and so 

 that the open end looks upward, i.e., 

 if other soft parts of its vicinity y\ hich 

 also close this are disregarded, [p. 37] 

 Bent flat, it shows a more or less dis- 

 tinctly H-shaped chitinous plate, with. 

 yery broad side parts, yvhich — in full- 

 groyvn larvae — become confluent behind 

 into a simple, broad plate, and only 

 leave an oval hole in front of them for 

 the passiige of the discharge duct of the 

 salivary glands, but posteriorly bear the 

 four wing-shaped processes (two large 

 upper, or in the outspread plate outer 

 ones, and two smaller, slenderer in- 

 ferior or inner). On the anterior end 

 of the body, ill many genera, oral hooks 

 are jointed to the short anterior side 

 parts. In the anterior curved excava- 

 tion of this lies in the membranous ex- 

 pansion a small corneous chitinous plate 

 which is pierced like a sieve and whose 

 nature has not yeX been more closely 

 investigated. It seems to me as if this 

 plate lay at the outlet of the salivary 

 ducts. It is especially distinct in Cepke- 

 nomyia larvae. It is wanting in sev- 

 eral others. 



In, young larvae the pharyngeal 

 framevv'ork consists only of tyvo chiti- 

 nous rods which are united in front by 

 a chitinous band ; these chitinous rods 

 radiate out behind in little wings. A 

 (similar) pharyngeal framework occurs 

 in all other muscid larvae,. and corres- 



ponds in the perfect insect to the cliiti- 

 niius flame of the proboscis. I have 

 repeatedly convinced myself that such 

 is really the case, since I have opened 

 the coarctate pupae of CcphciioDivia 

 and Gastropltilus before the emergence 

 of the flies. Since in these genera, as 

 we will see later, the nymph is tightly 

 enclosed by the pupaiium, it can be 

 noticed how the already freed phar\'n- 

 geal franiev>ork, which remains at- 

 tached to the pupaiinm, rests in the 

 mouth-fissure of the nymph, and is 

 drawn out of it as soon as the nymph 

 is taken awav or the lower lid is lifted 

 ort". It is also easy to form ail idea that 

 the pharyngeal framework together yyith 

 its internal parts corresponds to the 

 proboscis of the fly- if it is observed 

 how other inuscitl or syrphid larvae 

 yvhile alive project and Withdraw this 

 exacfh' as the fly does its proboscis. 



In Hvpodeinua the mouth-parts un- 

 dergo a retrograde metamorphosis from 

 the second stage (after the first molt) ; 

 the oral hooks disappear, and therewith 

 all the external mouth-parts, but the in- 

 ternal pharyngeal framework remains. 



4. The oestrid larvae show antennae 

 (at least rudimentary ones) above the 

 mouth-parts ; these have the appear- 

 ance of corneous or usualh' membranous 

 knobs, and in the latter case are pro- 

 vided yvith one or two ocelli-like points. 

 Subulate, many-jointed antennae, such 

 as occur in many muscid larvae, are 

 never found. 



5. All possess an anus, which lies 

 on the last ring, under the stigmatal 

 plates, and is very small. 



