EXPLANATION OF PLATE IV. 



•, 1. Pupa of Culex dissimilis, Theo. ; lateral view. 



2. Labium, or inner mouth structure of tlie larva of C. dissimilis, dissected out, and 



seen with a magnification of 350 diameters. 



3. '^ Under lip " (of Meinert) of the same larva, at the same scale of magniBcation. 



4. Maxilla and palpus of the same larva, as seen with the same magnification, but 



drawn on a smaller scale. 



5. Mandible of the same larva, seen and drawn in the same manner as the maxilla. 



6. Structure under the labrum of the same larva, on the same scale as Figs. 2 and 3. 



7. Labrum of the same larva, drawn on a slightly smaller scale than Fig. 6. 



8. One of the brushes of the same larva, on a still lower scale; the comparative size 



of the parts is shown in Fig. 9. Muscle structure omitted, leaving the cliitinous 

 piece on which the hairs are socketed. 



9. Diagram of the head of the same larva, showing the muscles that work the brushes, 



and the situation of the labrum ; dorsal view, with all other structures omitted. 



10. The siphon and anal segment of Cidex niyrocvstcdis, Theo. ; lateral view. 



11. Pupa of C. nigrocostcdis, lateral view. 



12. Siphon of larva of Culex lividocostalis, Graham; lateral view, the ventral side to the 



left. 



13. One of the spines of the same siphon more magnified. 



14. Pupa of C. Uvidocostcdis, lateral view. 



15. Siphon of the larva of Cidcx jmUidothoracis, Theo, ; lateral view, the ventral side to 



the right. 



16. Siphon of the larva of Scutomyia mars/udli, Theo, : lateral view, the ventral side to 



the left. 



17. Spines on the same siphon more magnified. 



18. Anal segment of the same larva ; lateral vie\r, the ventral beard below. 



19. Head of the larva of Culex dissiiinlis, Tiieo.; lateral view, Avith all the plumes and 



hairs removed to show the relative situation of the mouth parts: — b, brush; 

 d, maxilla ; e, palpus ; /, mandible. 



