MOTIONS OF INSECTS. 479 



divers. Of this kind are the aquatic bugs (Gerris lacushis, Hydrometra 

 stagnorum, Velia rivulorum, &c. Latr.). The first can walk, run, or even 

 leap, which it does upon its prey, as well as swim upon the surface. The 

 second, remarkable for its extreme slenderness, and for its prominent hemi- 

 spherical eyes which, though they are really in the head, appear to be in 

 the middle of the body rambles about in chase of other insects, in con- 

 siderable numbers, in most stagnant waters. The Velia is to be met 

 with chiefly in running streams and rivers, coursing very rapidly over their 

 waves. * TThe two last species neither jump nor swim. The species of one 

 genus of this group (Halobates Eschscholtz) course about on the surface 

 of the sea between the tropics, and are remarkable for being the only in- 

 sects that have adopted the sea for their abode 2 , at least if we except the 

 genera of beetles JEpus, Pogonus, Bledius, Hesperophilus, &c., which burrow 

 in the sand while covered with the tide, and thus are partially inhabitants 

 of the ocean. 3 One species of Halobates (H. Streatfieldana Templeton) 

 was captured nearly midway between the continent of Africa and America, 

 by Colonel Streatfield, 87th R. T. F., where numbers of them attended the 

 Medusae. 4 



I am next to say a few words upon the motions of insects that burrow, 

 either to conceal themselves or their young. Though burrowing is not 

 always a locomotion, I shall consider it under this head, to preserve the 

 unity of the subject. Many enter the earth by means of fore-legs particu- 

 larly formed for the purpose. The flat dentated anterior shanks, with 

 slender feet, that distinguish the chafers (Petalocera) most of which in 

 their first states live under ground, and many occasionally in their last 

 enable them to make their way either into the earth or out of it. Two 

 other genera of beetles (Scarites and Clw'ma Latr.) have these shanks 

 palmated, or armed with longer teeth at their extremity, for the same 

 purpose. But the most remarkable burrower amongst perfect insects is 

 that singular animal the mole-cricket (Gryllotalpa vufgaris). This crea- 

 ture is endowed with wonderful strength, particularly in its thorax and 

 fore-legs. The former is a very hard and solid shell or crust, covering 

 like a shield the trunk of the animal ; and the latter are remarkably fitted 

 for burrowing, both by their strength and construction. The shanks are 

 very broad, and terminate obliquely in four enormous sharp teeth, like 

 so many fingers: the foot consists of three joints the two first being 

 broad and tooth-shaped, and pointing in an opposite direction to the teeth 

 of the shank ; and the last small, and armed at the extremity with two 

 sharp claws. This foot is placed inside the shank, so as to resemble a 

 thumb, and perform the office of one. The direction and motion of these 

 hands, as in moles, is outwards ; thus enabling the animal most effectually 

 to remove the earth when it burrows. By the help of these powerful 

 instruments, it is astonishing how instantaneously it buries itself. This 

 creature works under ground like a field-mouse, raising a ridge as it goes ; 

 but it does not throw up heaps like its namesake the mole. They will 

 in this manner undermine whole gardens ; and thus in wet and swampy 

 situations, in which they delight, they excavate their curious apartments, 

 before described. The field-cricket (Gryllus campestris) is also a burrower, 

 but by means of different instruments ; for with its strong jaws, toothed 



1 Curtis, Brit. Ent. t. ii. a Burmcister, Manual of Ent. 567 



5 Spence in Tfans. Ent. Soc. Lond. i. 180. 

 4 Templeton in Trans. Ent. Soc. Lond. i. 230. 



