38 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bllll. 



of the labella described by Graham-Smith (1030) in the feeding oper- 

 ations of the blowfly Call'ipJwra. 



In the "non-feeding position" of the labella of Callifhora^ the 

 oral or pseudotracheal surfaces of the labella are apposed to each 

 other, and the posterior ends of the labella lie back against the medi- 

 proboscis in repose. In wliat Graham-Smith calls the "filtering po- 

 sition", the labella of the blowfly are opened out to form a flat, oral 

 disk; and the pseudotracheal surfaces of the labella are applied to the 

 food dissolved in the fluids regurgitated from the proboscis, so as to 

 take uj) the fluid through the interbiflcl spaces, and strain out the 

 particles which cannot pass through the filter apparatus. In what he 

 calls the "cupping position", the outer edges of the oral disk, formed 

 hiN the labella, are turned do^vn to form a marginal rim around the 

 now concave disk, which forms a cupping apparatus. In the so-called 

 "intermediate position", the labella are separated sufficiently to par- 

 tially expose the prestomal teeth and enable them to participate, to 

 some extent, in the operations of the labella as they sponge up the 

 fluid food through the filter apparatus; while in the so-called "scrap- 

 ing position", the labella are everted sufficiently to completely expose 

 the prestomal teeth, which are brought into play to scrape, or rasp, 

 the food substances. In the "direct feeding position", the labella are 

 everted and drawn back against the mediproboscis, out of the way of 

 the tip of the food channel, through whose orifice the liquids, and 

 small particles contained in them, can pass directly into the food chan- 

 nel formed by the labrum and hypopharynx (Fig. 4, E and F). 



The mouth parts of the muscoid type of fly described above be- 

 long to the absorbent, or sponging type (according to ]Metcalf and 

 Flint, 1932), in which the labella are fleshy lobes, unfitted for piercing. 

 In this type of mouth parts (Fig. 4, E and J), liquids entering the 

 pseudotracheae, probably by capillary attraction, pass into the tra- 

 cheal trunks, or collecting channels, and through the prestomum. on 

 "oral" aperture, into the food channel (called the food meatus by> 

 Snodgrass, 1935) formed by the labrum. It^ and the hypopharynx. A;?,, 

 shown in Fig. 4, F, Hadial miLScles, extending between the epi-'f 

 pharyngeal and anterior labral walls, may possibly serve to dilate thera 

 lumen of tlie food channel, and aid in taking up the liquids into this*] 

 region. 



From the food channel, the liquid food is drawn up into the 

 chamber of the first food pump, or fulcral pump, located in the floor 

 of the fulcrum, ju of Fig. 4, E. This fulcral pump (referred to as the 

 basipharynx by Peterson (1916), or the cibarium by Snodgrass 

 (1935), etc.) is formed by a double, or false, floor in the interior of the 

 fulcrum, fii^ whose firm outer wall, v of Fig. 4, E, forms the floor of f| 

 the pump chamber, while the pliable "false floor", d^ forms the rooff 

 of the pump chamber. Muscles extending from the pliable roof off 

 the chamber d to the anteclypeus, ao. etc., contract, and dilate th^fl 

 lumen of the pump, to suck up the liquid food. When these muscles'^ 

 relax, the liquids are compressed and forced back into the alimentaryi 

 tube behind the fulcrum. In the housefly, regursritation into the food 





