38 ON THE ANATOMY OF THE FLY. 



DESCRIPTION OF PLATE II. 



This plate represents the hard parts of the head and proboscis, with the 

 three anterior larval segments for comparison with those of the proboscis 



Fig. 1. An anterior view of the head of the male, with the part 

 belonging to the fifth segment colored ; the hairs are removed and are 

 represented only by their scars. X 10 diam 



Fig. 2. Posterior view of the head of the female showing the greater 

 width of the frontal plate ; colored like the last, x 10 diam. 



Fig. 3 and 3<t. Ventral and side views of the hard par tr. of the mouth 

 of the adult larva, consisting of a, the pharynx to which the appen- 

 dages bb are attached ; it is probably composed of the third segment 

 united to the true pharynx, as in the perfect insect. The other parts are 

 represented on a larger scale in figs. 4 and 4, x 25 diam. 



Figs. 4 and 4a. Ventral and side view of the first and second segment 

 of the same, c, second segment, rf, larval hooks or mandibles, e, labrum? 

 / g* parts of the first segment, constituting the margin of the mouth, x 7 5 

 diam. 



Figs. 5 and 50. The triangular opening of the mouth of the perfect fly, 

 seen from the front and side ; a a, rudimentary mandibles; &, apodemes of 

 the same; c, labium ; c?, labial appendages, x 75 diam. 



Fig. 6. The labium and tongue. X 25 diam. 

 Fig. 6a. The apex of the tongue x 75 diam. 



Fig. 66. Section of the mouth, through the lower part of the oper- 

 culum . 



Fig. Qc. Section of the second joint, through "the upper part of the 

 operculum. 



Fig. 7. The operculum composed of the labium and terminal lobes 

 of the maxillae, with their apodemes. x 25 diam. 



Figs. 8 and 9. The mentum. x 25 diam. 



Fig. 10. Scale-like basal lobes of maxillae, with the basal bands bearing 

 the maxillary palpi, x 12 diam. 



Fig. 11. The fulcrum, consisting of the dorsal plate of the third segment 

 the epistoma and the chitinious pharynx united, dorsal view, x 25 diam. 

 Fig. 12. The same with its muscles attached. 



Fig, 13, Side view of the same, to show the attachment of the muscles; 

 a, exsertor muscles ; b, pharyngeal musdes; c, c/, muscles to apodemes 

 of the operculum ; e, muscles of salivary valve. 



Fig 14. Section through the lower part of the pharynx, showing the 

 central cavity and the disposition of the muscles by which it is opened. 



. Figs. 15 and 15a, Small scale for protecting the bend of the pharyngeal 

 tube, developed in the wall of the same. 



