Falconer : Ahnorviality iti Spiders. 201 



jecture, therefore, as explicit knowledge is denied us, that some 

 other influence in addition to darkness is at work to produce 

 atrophy of the organs of vision. 



Combinations of male and female characters in the same 

 individual are exceedingly rare amongst spiders, the four noted 

 below being, so far as I can discover from the literature at my 

 disposal, the only ones which have occurred, or at least been 

 considered worthy of specific mention. The same phenomenon 

 is much commoner amongst insects, but in neither class is there 

 a genuine case of hermaphroditism, such as exists amongst the 

 mollusca, worms, and others of the lower animals, in which 

 either mutual or self-impregnation obtains, with subsequent 

 production of young, but all instances, at least amongst spiders,, 

 are marked by some structural imperfection in one or both sets 

 of copulatory organs, as that having regard to the mode of 

 reproduction amongst them, it may be taken for granted that 

 these organs are functionally inoperative. The first reference 

 to the condition is that of the Rev. O. Pickard-Cambridge in his 

 paper ' On New and Rare British Arachnida ' in the ' Proc. Dorset 

 Field Club,' Vol. XXII., 1902, p. 17. The example there re- 

 ferred to, Hilaira excisa Camb., was taken in Glamorgan, by Dr. 

 A. Randell Jackson, in igoi, and had one palpus of the male 

 and the other of the female form ; the caput bore the peculiar 

 structure which belongs to the male alone, and the abdomen 

 was also of the normal male form. Mr. Cambridge, also states, 

 that he once found a similar specimen in a collection of exotic 

 spiders, but it was lost or destroyed by some mishap before he 

 could make either a drawing or description of it ; further that 

 these were the only ones he had noticed among the many 

 thousands of spiders which he had had occasion to examine.. 

 The third example is recorded by Dr. Jackson in his ' Spiders 

 of the Tyne Valley,' p. 384, ' Trans. Nat. Hist. Soc. of Nor- 

 thumberland, Durham and Newcastle-upon-Tyne,' New Series^ 

 Vol. I., part III., a Porrhomma oblongum Camb., found at 

 Hexham, which had one male palpus, a female palpus, and a. 

 distorted epigyne. It was an examination of this specimen,, 

 kindly lent to me some years ago by its finder, that first evoked, 

 in me an interest in the subject of this paper — an interest which 

 was further stimulated and increased, when a short time after- 

 wards I myself obtained a most curious form of OEdothorax: 

 retusus Westr., which was included in a large gathering of the 

 same species which I made on the sandhills, south of Southport, 



1910 May I. 



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