PLATE L 



Figure 1. Ths alimentary tract of the larva of Tabanus albime- 

 dius. oes., oesophagus, pv., proventriculus. sl.g., 

 salivary gland, mg., mid-gut. mp.t., Malpighian 

 tubes. X 3. 



Figure 2. The alimentary tract of the larva of Stomoxys calcit- 

 rans, dissected out. si. d., salivary duct, ph., pharynx, 

 ch.t., chylific tubules, h.g., hind-gut, v., valve-like 

 constriction on the hind-gut. Other letters as above. 

 x 10. 



Figure 3. The chitinous framework of the pharynx and connect- 

 ed parts of the larva of Stonioxys calcitrans. lr., 

 labrum. x 66. 



Figure 4. The head of the larva of Tabanus albimedius, show- 

 ing the mouth appendages, lr., labrum. p., palp, 

 mx., maxilla, ant., antenna, md., mandible, sp., 

 the area of spines. Drawn from a cleared preparation. 

 X66. 





