70 MOSQUITOES OF NORTH AMERICA 



appendage, the clasp-filament (b) and also occasionally certain lobes near base 

 or tip (c), designated as subapical or subbasal lobes. There are three sets of 

 paired basal appendages, the harpes (d), harpagones (e) and unci (f). The 

 penultimate segment generally has a pair of setose appendages, the basal ap- 

 pendages (g). In the simplest forms these smaller basal appendages, harpes 

 and harpagones are absent, as in Anopheles, though the unci are always present. 

 In the succeeding higher forms the harpes appear and still later the harpagones. 

 The harpes are present in all the genera above Anoplieles, Aedeomyia and 

 Uranotcenia and are probably homologous throughout the group as they have 

 essentially the same form in all, only becoming modified in Culex. The harpa- 

 gones, or at least a third pair of appendages, appear in all the highest forms, but 

 it is doubtful if they can be regarded as strictly homologous as they seem to have 

 arisen three times independently, once in Aedes, once in Culex and once in 

 the sabethid line. We have, however, uniformly designated the third pair of ap- 

 pendages as harpagones. Several different lines of modifications are found in the 

 different groups. The Anopheles are all very simple, having besides the side- 

 pieces, clasp-filament and unci, nothing but various spines and hooks without 

 forming definite accessory clasping organs. In the most specialized species, 

 such as hellator and harheri there is a rounded basal lobe bearing a tuft of long 

 hairs. N"ext to Anopheles in simplicity comes Aedeomyia, in which there are 

 present only somewhat complex unci. The side-pieces have a small basal lobe 

 while the clasp-filament has a multiple terminal spine. Next comes Uranotcsnia, 

 in which there is a complex series of small basal appendages perhaps represent- 

 ing divisions of the unci, but no recognizable harpes. The side-pieces bear a 

 more or less well-developed conical basal lobe. Next come the lower Sabethids, 

 Lesticocampa and Johlotia, together with the lower Culicids, Megarhinus, Ban- 

 croftia, Mansonia and Culiseta. These have the harpes well developed but no 

 harpagones. There is generally present a basal lobe to the side-piece, which in 

 Mansonia becomes modified into a ribbon-like appendage or a rod carried on the 

 basal lobe. In the Sabethid line a division of the small basal parts occurs, so 

 that in many forms a third pair of appendages or harpagones can be recognized. 

 The characteristic development of the line, however, takes another direction, 

 that of the modification of the clasp-filament, which becomes lobed and dis- 

 torted, culminating in Sdbethes, where a truly wonderful structure is produced. 

 In a few forms the clasp-filament is reduced to a rudiment, its place being taken 

 functionally by an expanded outer angle of the side-piece, and in others a basal 

 lobe of the side-piece is developed (as in Wyeomyia eloisa and allies) in which 

 case the clasp-filament is more or less reduced. In the Aedes line the lower 

 forms are simple. In calopus there are no harpagones and in other tree-hole 

 species the first rudiments of these organs are seen as a conical basal lobe of the 

 side-piece bearing a seta (for instance in walTceri, alhonatata, etc.). Later this 

 becomes developed into a rod bearing a filament. Sylvestris and fuscus have no 

 harpagones, but in these cases the organs have not improbably retrograded. In 

 the Janthinosoma group the rod bears several filaments and in Psorophora a 

 capitate tip is developed with a large group of filaments. The harpagones of 



