The Feet of Insects. 397 



marshy ground. Some of them are carnivorous, and, like the 

 Dolicliopus and Empis, flies who prey upon smaller insects, have 

 the thighs armed with spines, as in fig. 13, by which the 

 struggles of its prisoner are soon ended. I need not say that 

 in this tribe the pulvillus is always very small, and often alto- 

 gether absent. 



But whilst we are looking at the foot of a fly, let us not 

 pass unheeded the variations in the tarsal joints. Here is the 

 leg of a merry little fellow of the Empis family (Hilar a cilipes, 

 fig. 13) ; he feeds chiefly on the nectar of flowers, and is easily 

 recognized by his dilated fore-metatarsi, but he also enjoys a 

 small fly or two, and has a sharp little proboscis on which to spit 

 them and leisurely suck their juices. These pretty little Hilara, I 

 cannot help talking of them ; they assemble in myriads over the 

 running rivulets and the calm bright waters of the Cherwell, 

 revolving in horizontal or oblique circles, crossing each other 

 in a mazy dance, sweeping away quite suddenly, as if impelled 

 or chased by fairy foes, anon returning to their merry sport in 

 the summer sunshine. These dilated tarsi belong only to the 

 male, and are given that he may restrain the movements of his 

 volatile mate. 



Fig. 8 is the leg of Bibeo marci, a very abundant heavy 

 black fly, found in meadows round London during the month of 

 May, with a remarkable prolongation of the fore-tibia into a sharp 

 spine, with which it retains its prey. Another species has a 

 perfect coronet of spines round its tibia. 



Figs. 7 and 9 are legs of those flies called Syrphidoe, which 

 resemble small wasps, and hover over flowers with a peculiar 

 vibration of their wings ; the curved and toothed femur is for 

 some special purpose, I doubt not, but I cannot tell what it is ; 

 they are honey-loving insects, and difficult to catch, from 

 ■springing sideways very quickly. 



I must now conclude a paper that is, I fear, too long already, 

 with the foot and leg of a flea. The Pulex irritans is ranked with 

 the Diptera now, though wingless, because of its suctorial 

 apparatus allying it to the Gnat family. 



No pulvillus, indeed, does this restless little pest require, 

 but it wants muscular power in no ordinary degree to leap 200 

 times its length without any aid from wings, and therefore look 

 at the long, large coxa, the stout femur, the spiny tibia, and 

 strong claws ; not only lobed, and long, and sharp ; but striated 

 (fig. 12 c), and crenated, and for hitching in blankets, and 

 creeping, and clinging, and tickling, — finished to perfection* 



