THE DEINOCERITINES 191 



respect, using chiefly its mandibles to seize its prey, thougli the antennae evi- 

 dently assist in the act of prehension. Eucorethra, in short, is close to 

 Anopheles in the Culicini, and it is possible to imagine the evolution of this 

 tribe from some ancestor similar to Eucorethra; but the Sabethini can not be 

 derived therefrom, nor indeed from any living Corethrinse known to us. 

 The Culicini may be divided into four groups on general relationship : 



I. THE DEINOCERITINES. 



The deinoeeritines form a compact group of three genera, Deinocerites, Dina- 

 namesus, and Dinomimetes. We place this group first, largely because it is im- 

 possible to interpolate them anywhere and they are in many respects much 

 specialized. The antennae are essentially alike in the sexes and are more or less 

 elongated, being the most generalized of any mosquito antennae, although this 

 is more probably a case of degeneration. The antennae are affected by speciali- 

 zation, and peculiarly modified. All the species live in holes in the earth exca- 

 vated by certain species of crabs, the larvae living in the water at the bottom, the 

 adults frequenting the upper parts of the burrows. Special sensitiveness of the 

 antennae seems necessary to enable the insects to avoid their crustacean host when 

 it returns to its abode, or the fragile mosquitoes, resting upon the sides of the 

 narrow channel, would be dashed into the water beneath and destroyed. There- 

 fore this character, being affected by specialization, largely loses its value in 

 classification, so that we the more readily concede to the group a high position; 

 in fact, from the genitalia, they seem to be a specialization of Culex. The larvae 

 are of a culicine type without any markedly generalized characters. They have 

 peculiar mouth-parts, probably only a special adaptation to their mode of life. 

 The anal gills are absent, which is an unexpected specialization. The larvae, as 

 far as we know them, and the male genitalia are remarkably uniform, scarcely 

 offering specific differences even. This indicates great stability for the group, 

 which must be well adapted for its habitat, and not now undergoing evolutional 

 change. The sexes present practically no secondary differential character, which 

 confirms the established character of the group and indicates that it has been 

 long separated from the other Culicini. 



Two characters shown in the group deserve special mention. The male 

 genitalia, very stable and uniform throughout the species, are of a more special- 

 ized type than in any other mosquitoes, an intensification of the Culex type with 

 certain special modifications. The other character is the presence of setae upon 

 the postnotum in one genus, Dinomimetes. It was at first supposed by us that 

 this indicated the genus to belong to the Sabethini, and that its otherwise great 

 resemblance to Deinocerites was due to convergence owing to similar environ- 

 ment. But further study showed that both the male genitalia, so unique in 

 structure, and the larvae with their peculiar adaptations, were scarcely spe- 

 cifically distinguishable. The genus is obviously a near relative of Deinocerites 

 and we are even in doubt whether these setae upon the postnotum are of specific 

 value, since two specimens before us seem to lack them. The character is most 

 probably one of recent acquirement, but we are at present unable to conjecture 

 its full significance. 



