90 INSECUTOR INSClTl.Tv MI'NSTRUUS 



and then again disappears (PI. Ill, fig. 5; PI. IV, figs. 7-11). 

 The third plate arises as a tooth on the second, as in Culex 

 stenolepis (PI. IV, fig. 7). This tooth enlarges, as in Culex 

 coronator (PI. IV, fig. 8), becomes basal, as in Culelx factor 

 (PI. IV, fig. 9), separates as in Culex declarator (PI. Ill, 

 fig. 5), and finally becomes quite detached as in Culex quinque- 

 fasciatus (PL IV, fig. 11). The fourth plate is small and 

 often hard to find, possibly absent. It occurs in the form of 

 a pair of rods protecting the anus (PI. Ill, fig. 1; PI. IV, 

 fig. 12). 



The lobe of the side piece bears primitively three setse. To 

 these certain others are added and finally the lobe becomes 

 subdivided, but only slightly modified. In one form, Pha- 

 langomyia, there is a modification of the side pieces, which, 

 though striking, is not fundamental, as the three primitive 

 setae can be easily traced (PI. Ill, fig. 1). 



The second general group, Melanoconion, is much more 

 modified. The harpes have the tip comb-shaped, the spines 

 in a single row, the basal arm represented by a rounded process 

 or absent. The divisions of the unci are complex, and I' am 

 not sure of their homology. The difificulty of the study is 

 increased by the fact that clear mounts are not always to be 

 had of critical species of which the material may be scanty. 

 Apparently there are primitively four plates as in Culex (Tin- 

 olestes) latisquama (PI. IV, fig. 14) and Culex (Micraedes) 

 chalcocorystcs (PI. IV, fig. ]•")). The first is a large outer 

 sheathing plate, shown disjointed from its socket in the figure; 

 the second a spatulate structure ; the third large and furcate ; 

 the fourth rod-like with modified tip. In Deinocerites, the 

 outer plate seems to be gone, the second elongated (PI.. IV, 

 fig. 13). In the higher forms, the fourth plate seems to have 

 disappeared, while the second assumes the form of a long 

 hook, recurved around the other parts, as for example in 

 Culex (Micraedes) bisulcatus (PI. IV, fig. 16) and Culex 

 (Chccroporpa) educator (PI. IV, fig. 17). 



The lobe of the side piece in Melanocomon begins simply, 

 but becomes complex and sul^divided in the higher groups, 

 notably in Choeroporpa and Carrollia. 



