Kew : Lincolnshire Pseudoscorpions. 



207 



circumstance, 'serving the purpose of dispersal. The creatures, 

 thus clinging by closure of the shell, are carried through the air 

 and along the ground just as Pseudoscorpions are while clinging 

 by a closed pincer to the legs of flies, harvest-men, etc. Oper- 

 culate snails, moreover, occasionally cling accidentally to legs 

 of insects, by closure of the operculum. And in this connection 

 one may refer also to the clinging of certain biting-lice to winged 

 parasitic bird-flies : a habit which doubtless secures dispersal."* 

 Dr. Lukis, referring to the case in which a house-fly had four 

 Pseudoscorpions on the same leg, has doubted whether the 

 attachment can be accidental. If this be the case, he says, 

 'I am at a loss to conceive how so many . . had attached 

 themselves to one limb ? If the fly had accidentally placed the 

 limb in a nest of these insects, it seems natural to believe that it 

 would have had sufficient sensibility to withdraw it ere the whole 

 family had time to attach themselves.' In reply, however, one 

 might bring forward cases, of which I have elsewmere given 

 particulars, of a water-bug with three bivalves accidentally 

 attached to its toes — of newts with four, toads with six, and 

 crayfish with eight shells similarly attached. It might be 

 argued, perhaps, that the attachment, at first accidental, but 

 proving valuable as a means of dispersal, has been encouraged 

 by natural selection, and has thus the character of a separate 

 instinct. Professor Moniez, who appears to go a step further, 

 has supposed the attachment of Pseudoscorpions to be inten- 

 tional, the creatures being believed to seize the legs of insects 

 for the express purpose of getting themselves transported. He 

 relates that each time he had wished to exhibit Pseudoscorpions 

 to his pupils he had easily obtained specimens by the following 



* At a meeting- of the Entomological Society of London, in 1890, 

 Dr. Sharp exhibited Ornithomyia avicularia, from Dart ford, to which 

 were adhering - — apparently by their mandibles —several specimens of 

 a mallophagous louse (1). The Ornithomyia is a flying Dipteron that 

 infests birds, and it is believed that Mallophaga arc transferred by this 

 means from one bird to another (2). Lt.-Col. Walker (3), moreover, has 

 recently reported the capture of a specimen of the same fly which was 

 leaving- a recently-shot blackbird, and to which, hanging- on like a bulldog, 

 was a biting-louse agreeing with Denny's figure of Nirtnus merulensis. 

 This was the second instance which had come to the observer's notice of 

 a mallophagous insect attaching- itself to Ornithomyia ; in both cases it 

 adhered to the posterior part of the hind-body. (1) D. Sharp. Trans- 

 actions of the Entomological Society of London, 1890, p. xxx.; [2) D. Sharp, 

 'Cambridge Natural History.' Y. (1895), pp. 350-1; (3) 1 1 . J. O. Walker, 

 1 Bird-louse Changing Hosts,' Science-Gossip (n.s.), VII. (1900). p. 101. 

 1901 July 2. 



