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



minute, scattered, scale-like hairs. Length of tenant hairs, from the anterior inferior 

 margin of a tarsal joint of Ocijpus, '009 inch. 



On the hands of a very small Staphyline, I found only about 7 or 8, proportionally very 

 large tenent hairs ; I think they arose only from the fourth tarsal joint. The specimen 

 was unfortunately given away before careful notes or drawings were made, and I have not 

 vet succeeded in recovering it. It appeared worth record, however, to show what inter- 

 esting modifications may be looked for Avhen a complete examination of insects' tarsi has 

 been made. 



The Staphylinidse are very interesting objects to the microscopist, in connexion with 

 various points in their minute structure. Nowhere will better examples of the earliest 

 modifications of hair to suit tenent purposes be found than amongst many of the smaller 

 examples of the family. Some of these are figured (figs. 25, 26). From observations on 

 such of these brachelytrous insects as possess tenent hairs in the most rudimentary deve- 

 lopment of this special type of structure, where they are not connected with sexual pur- 

 poses, we ascertain that the specialization consists essentially in a simple flattening of the 

 hair from above downwards, and an absence of chitinous ossification towards its extremity. 



The male of Cicindela campestris has cushions on its anterior tarsi, the hairs compos- 

 ing which well illustrate the above statement by the slight degree of this modification 

 Avhicli they present (fig. 27). 



The suckers of the male Dytlcus furnish a remarkable example of appendages for 

 sexual purposes *. It now became desirable to ascertain the exact structure of these. 

 All are circular in their outline, and concavo-convex in form (fig. S3), the concavity being 

 on the under surface ; the two proximal ones are much larger than the remainder, which 

 are nearly alike in size : the outer of the two great ones is -^^ inch in diameter ; these 

 two are fringed round their outer margin with remarkable branching hairs (fig. 35), which, 

 when the apparatus is used in the water, will by preventing too close contact also prevent 

 the water from insinuating itself so as to destroy the vacuum ; and if the female struggle 

 out of water, by retaining liquid for some time around the sucker, they will in like manner 

 under these altered conditions equally tend to preserve the effectual contact. There is 

 no direct connexion between the tarsal joints and the centre of the suckers, whether of 

 a muscular nature or otherwise, as has been asserted. The pedicles of the two large 

 suckers are so short that the latter appear to be sessile ; these latter pedicles are of a 

 densely membranous texture, cutting like tendon ; and my present belief is that they are 

 quite solid, though I have not yet had time to verify this supposition. All the suckers 

 are siipported in an extended condition by rays of a firmer consistency than the remain- 



* " In many species " (of the Dyticidse) " the hasal joints of the four anterior tarsi are dilated, whilst in some of 

 the larger species the two anterior male tarsi have the three basal joints enlarged into a broad and nearly circular 

 shield, convex above, fringed with fine hairs, and cushioned beneath, or, rather, covered with a number of minute in- 

 verted caps [?cups] with several larger portions resembling suckers, varying in number and size in the variou,'- species . 



This structure enables the male to retain his situation upon the back of the female during copulation, the 



rugosities upon the thorax and elytra of the latter being also similarly serviceable." — Westwood, Introd. vol. i. p. 96. 



The remarkable increase of holding power which is obtained by the traction of these limbs to each other, and, when 

 acting coujointl)^ to the body of the beetle, does not appear to have been specially noticed. 



