MR. TUFFEN WEST ON THE FOOT OF THE FLY. 415 



that the fibre whicli can be so readily demonstrated, passing to the root of each of these 

 structures represents chiefly muscle rather than nerve. 



Tenent hairs are constantly liable to be injured from extraneous causes, especially in 

 insects of cursorial habits. Wherever met with, they are invariably found to be accom- 

 panied by hairs arranged in series along the margins of the tarsal joints to which the 

 tenent hairs are attached. From the office they perform in the economy of the insect, 

 these may appropriately be termed " guard-hairs." I have ascertained, by direct obser- 

 vation, that the male Carabidce and Harpalides, in which they are remarkably stout and 

 strong (see figs. 20 to 23, PL XLII.), walk upon the ends of these guard-hairs ; the much- 

 worn condition in which they are found on Ground-beetles captured in the usual Avay also 

 testifies to the above fact. During progression, the tenent haii-s touch but slightly, if at 

 all, the general surface of the ground ; but during the powerful excitement of the male of 

 these beetles at the time of coitus, the guard-hairs are pressed aside, and the tenent hairs 

 brought into close contact with the surface of the female, so as to form a powerful appa- 

 ratus for adhesion. The habits of some amongst the Carabidse, of living upon trees, of 

 others, " amongst the branches of umbelliferous and other plants during the autumnal 

 months, where it is not improbable that they ascend for the purpose of feeding upon the 

 ripe seed*," point perhaps to the possession of tenent hairs by both sexes amongst 

 beetles having these habits. 



Even climbing insects, as distinguished from the ground-loving beetles, have the guard- 

 hairs well developed, though on a slighter type of structure ; and the marginal hairs 

 without expansions on the flaps of the Ely's foot are a still more delicate form of guard- 

 hairs. It is these latter, which are far more readily visible than the tenent hairs on 

 the Fly's foot, which have, I suspect, led to some errors of the earlier observers of this 

 structure ; they are fine, sharp, slightly bent downwards towards their points, and might 

 very readily be taken for minute hooks. 



Notwithstanding the protection afforded by the guard-hairs, the delicate organs which 

 they enclose are in some insects never to be found perfect. This is the case with Necro- 

 l^liorus (fig. 57) ; and I have found a specimen of Ocyims in Avhich they were almost 

 equally injured (fig. 24-, i.) ; in Harpalus I have less often met with this condition of the 

 organs. 



I figure the tarsi of various Insects, of a Fodura, and of Acari, in which tenent hairs 

 are present in small number, varying from one to five ; it will be seen how generally, in 

 these cases, they are situated above the single, double, or triple claw. 



The remarkable scale-like organs on the anterior and middle pairs of legs and round the 

 body of Chelymorpha testudinaria are examples of another modification (so I'ar as is yet 

 known, unique) of tenent hairs. In addition to these, there is present at the end of each 

 distal tarsal joint, arching over the ungues, a pair of tenent hairs, like those mcutioued 

 in the last paragraph (fig. 64). 



By favour of my friend G. Hodge, I am enabled to present a figure of some appendages 

 to the legs of a marine Acarus (fig. 68) taken in deep water off Seaham harbour, and 



* Westwoodj loc. cit., passim. 



