>26 



MK. W. WESCHE ON THE LABIAL AND 



Family Anthomyiid^. 

 Subfamily Anthumyiina. 

 Hylemyia cardui, Meig. (PI. 9. fig- 27). 

 H. pullula, Zett. (very small). 

 Lasiops ctenoctema, Kow. 

 Anthomyia radicum (Linn.). 

 A. pluvialis (Linn.). 

 A. sulciveniris, Zett. 

 Phorbia floccosa ?, Macq. 

 Pegomyia bicolor, "Wied. (PI. 9. fig. 29). 



Subfamily Homaloinyiince. 

 Azelia Macquarti, Stag. 



Family SARCOPHAGiBiC. 



Myiocera carinifrons, Fallen. 



Family Muscid>«. 



Graphomyiamaculata, ScoTp. (PI. 9. fig. 31). 

 Musca domesiica, Linn. (PI. 8. fig. 12). 

 M. corvina, Fabr. 



Acalyptrate lluscidce. — In a number of species in the Acalyptrate Muscidae the palpi 

 are quite fully developed, but, on account of the small size of the flies, are very difficult 

 to make out. The maxillae, when present in Diptera as hitherto observed, have only 

 tlie laciniae and palpi present, the galse having aborted. Such a state of things is seen in 

 the Culicidse, Simulidce, Tabanidse, and Asilidse. In a small and common species of 

 Ephydra (PI. 9. figs. 21 & 22) I found a maxilla which has all the parts represented. 

 This species has also the remarkable dentition previously alluded to. 



In Balloptera combinata, Linn. (PI. 9. fig. 18), an arrangement is seen differing from 

 those already mentioned, but there are several species that follow this type. It is 

 difficult to say whether the palpi or the laciniae are aborted. Comparing this species 

 with the Syrphidse one is inclined to think that the palpi are absent. 



In Nemopoda cylindrica, Fabr. (PI. 9. fig. 19), maxillary palpi can be made out, but 

 the cardines are so faintly chitinized that their presence can only be suspected. In 

 the nearly related Sepsis cynipsea the cardines and stipites are exceedingly short. 



In Sphcerocera suhsultans, Pabr., the four palpi are found in a more developed state 

 than any hitherto met with (PL 9. fig. 20.) 



In the figure a dorsal view is gA^en of the parts, showing the fulcrum, the mentum 

 through the transparent membrane, and the labrum above it. I have examined several 

 species of this family, but have only found similar palpi in Borborus sulUorum, Hal. 

 In Linwsina lugubris, Hal., L. sylvaiica, Meig., L.fiiscipeniiis, Hal., and Sphcerocera 

 deniiculata, Meig., the palpi were of much the same type as in _B. combinata 

 (PI. 9. fig. 18). 



Archaic Type. — The varying armature and shajie of the trophi in Diptera suggest 

 a speculation as to archaic types. 



I. The labium was probably short as in Tipula and has gradually elongated. The 

 labial palpi have remained at or near their original distance from the head, but have 

 worked round to the upper part so as to be of service. Where this has not occurred 

 (1) they have aborted as in the Syrphidse, Empidae, Bombylidae, Asilidae, Tabanidae, and 

 Culicidse ; (2) or they have followed the labella down, as in Lilophus (PI. 8. fig. 8). 



Siphona geniculata is an example of the extreme development caused by the advantages 

 gained by elongation. In this species many parts usually present on the labella, teeth, 

 and transverse expanding levers (ligulso) have aborted, and no traces of the maxillary 

 palpi are to be seen. Prom this we may infer that this type is more specialized, 



