292 w. wesche on the proboscis of the blow-fly, 



EXFLANATION OF THE PLATES. 



Plate 22. 



Pig. 1. Mentum or ventral plate on the proboscis of the Blow-fly 

 CaUiphora erythrocepliala, Mg., S dissected out, flattened, 

 and drawn to the same scale as the other parts of 

 the trophi of the same insect. To show the absence 

 of any median process and the characteristic chaetotaxy ; 

 the hairs and bristles on the mentum in the Brachycera 

 (with the exception of Haematopota) being in my obser- 

 vation much fewer in number. 



Fig. 2. Upper plate of the proboscis of C. erythrocephala, drawn 

 from a preparation in balsam, the action of which 

 has somewhat distorted the parts. To show the lateral 

 rods. 



Fig. 3. The labrum, hypopharynx, stipites and cardines of 

 the maxillae, and submentum (fulcrum of Lowne) 

 of C. erythrocephala, dissected out from the base of 

 the labium and drawn laterally. To show the stipites 

 and cardines in their normal position in the Muscidae ; 

 their usual function is lost, and they hinge on to 

 the labrum. Ir. labrum ; h. hypopharynx ; s. stipes ; 

 c. cardo ; sm. submentum. 



Fig. 4. The upper apodeme or lever, dissected out from the 

 the labium of the Crane-fly, Tipula oleracea, L., and 

 drawn to the same scale as the lower lever from the 

 same insect. To show the median suture, indicating 

 that it is a fusion of two rods, and the connection of 

 the anterior processes with the maxillary palpi. 



Fig. 5. Lower lever, dissected out from the labium of T. oleracea, 

 showing some of the structure, indicating that this part 

 is also a fusion of two rods. 



Fig. 6. Lower lever, dissected out from the labium of Bibio 

 marci, L. This occupies an identically similar position 



