378 MR. H. WALLIS KEW OX THE 



remarkable for the specialization of the male, in wliicli both primary 

 and secondary characters are unusually pronounced *. The 

 genital area of this sex is large and conspicuous, the first genital 

 plate being short and of peculiar character, while the second is 

 both long and broad, and under this latter are found two very 

 large structures, inappropriately called ram's-horn organs, to which 

 it will be necessary to recur. The fourth pair of coxae, which 

 bound the genital area anterioi-ly, difi'er much from those of the 

 female, being strongly concave behind and containing a peculiar 

 organ, the coxal sac of With (13). Of characters remote from the 

 genital area there is considerable diversity within the gi'oup ; there 

 are generally remarkable modifications in the legs of the first paii', 

 and these modifications are unusually well-marked in the present 

 species. The whole leg is greatly strengthened, with hurup-backed 

 tarsus, and greatly enlarged claws, the anteiior claw being of 

 peculiar shape with oddly turned extremity and with a process 

 along its anterior margin. Further, while the hand of the palp 

 is a little smaller than that of the female, the fingers when closed 

 at the tip have a wider gape. 



The ram's-horn organs already mentioned — supposed to be 

 tracheal in origin — have been studied in allied species by several 

 authorst. They are concealed under the second genital plate, whei-e 

 they lie in a highly contracted condition. Preserved specimens, 

 in exceptional cases, have them protruded externally ; and they 

 have been figured thus protruded by Simon (6), and after him by 

 Tomcisvary (7); and by With (16). It does not appear, however, 

 that they have been seen in action ; and the suggestion of Menge 

 (2) and Simon (6) that they are sperm-transmitters, perhaps intro- 

 mittent organs J, is erroneous, as also is that of Schtschelkanowzeft" 

 (17), who thought they niight be concerned in placing sperm- 

 masses on the ground. 



With regard to the other characters, except that With (14) and 

 SchtschelkanowzefF (17) have supposed the coxal sac to be a sense- 

 organ with some sexual significance, no suggestions appear to have 

 been made. The gape of the fingers, however, is obviously con- 

 nected wdth the grasping of hands already mentioned ; and the 

 observations now recorded show what is done with the I'am's-horn 

 organs and with the legs of the first pair. 



It was in May 1905, on the sand-dunes between Sandwich and 

 Deal, that I first saw the meeting of the sexes of this animal. On 

 txirning over a piece of tin, I found on its under surface a male 

 and female which had approached each other head to head, and 

 were actively fencing with the palps. The male at length dis- 

 armed the female by getting a firm grasp of the hands, which 

 were held fast during the whole of these preliminary proceedings. 



* With (14), pp. 132-3 ; With (16), p. 220 ; Kew (18), p. 47. 



t Menge (2), p. 17, pi. ii. lig-. 12 ; Hansen (8), pi. vii. fig. 2 Ji ; Croneberg (9), 

 pp. 456-7, pi. xi a. figs. 45-47 ; Bernard (10), pp. 423-6 ; Oiulemans (15), pp. 136-140 ; 

 Schtschclkanowzeff (17), pp. 6-14. 



;|; On the supposed occurrence of intromittent organs in this Order, rf. Lankcster 

 •(12), p. 256 ; and Croneberg (9), p. 39. 



