78 GNATS OR MOSQUITOES — CHAPTER VI 



tomentum. The third class of chitinous appendages are 

 the tarsal claws and epipodium, the latter of which is 

 essentially a compound hair, while the former vary in form 

 almost as much as do the scales. In the females these 

 claws are usually of simple form, and of no great size ; but 

 in the male, those of the fore and middle legs and more 

 rarely those also of the hind pair, are usually propor- 

 tionally large and armed with one or more accessory teeth, 

 and the two claws of the same leg may differ in size and 

 form. Those of the fore legs are generally the largest, 

 and the difference in size and form in the sexes is sugges- 

 tive of the function of those of the male being to grasp 

 the female. In many species, at any rate of Anopheles, 

 there is only a single compound claw on the fore leg, 

 the missing claw being apparently represented only by a 

 small projection at one side of its base. Varying as they 

 thus do, there can be no doubt but that the form of the 

 claws would, if generally noted, be capable of furnishing 

 valuable specific indications; but though valuable notes on 

 this point have been made by Ficalbi, and also by Arribal- 

 zaga, information on this point is wanting in the great 

 majority of species, and the circumstance that it is impos- 

 sible to properly make them out without mutilating a 

 specimen by mounting the legs, for the compound micro- 

 scope tends to render these characters not so useful as 

 others for the practical purposes of classification. The legs 

 are always thickly clothed with scales, and in the one or 

 two species of the genus Sabethes of Desvoidy, and of Mr. 

 Theobald's new genus Conchyliates, the sides of the tibiae 

 or tarsi of certain legs are provided with lateral fringes of 

 long scales so as to form a sort of paddle-shaped expansion ; 

 while in Psorophora and Mucidus the entire legs are shaggy. 

 The head is rounded, but wider than long, and bears the 

 usual appendages, all of these being represented, although 

 those forming the mouth parts, being modified to form the 

 style-like proboscis, differ markedly from the ordinary insect 

 foot-jaws, and present perhaps an even wider divergence 

 from the simpler forms than the suctorial mouths of most 

 other Diptera. 



