APHANIPTERA. 347 



Walker, reduces the number to thirteen ; and Theobald also has 

 a total of thirteen, though he includes one omitted by Verrall. 



Dale, in his History of Glanvilles IVooton, published in 1878, 



writes (p. 290), "Although only fourteen species of the Aphanip- 



tera have hitherto been described as British, thirty-eight have been 



taken in this parish." And he then gives a list of names, as Pulex 



furorts, on ferrets ; P. mtistelce, on weasels ; Ceratophyllus elon- 



gatuSj on the great bat ; C. vespertiliojiis, on the common bat ; 



C. musculi, on the common mouse ; C. muris, on the field mouse ; 



and so on ; considering as a distinct species, and giving a specific 



name to a flea if found on some animal from which he had not 



before taken it. His descriptions are remarkably concise ; some 



are as follows : — Ceratopsyllus merulce^ in blackbirds' nests, pallida 



picio-fusca^ length i line ; C. arvetisis^ in skylarks' nests, picio-fusca 



et obesa, length i line ; C. trochili^ in willow-wrens' nests, picio-fusca 



et oblonga ; and so on. All these and a number of others I believe 



to be merely Pulex avimn, varying a little in size and colour. The 



colour of a flea, however, depends a good deal upon its age, and 



also on the contents of the stomach ; while ^^obesa^^ was probably 



the result of a plentiful meal, or that the capture was a female 



containing eggs. 



Before entering into an anatomical description of the flea, I 

 shall refer to it from an historical and from a literary point of view. 

 The earliest mention of a flea that I have come across occurs in 

 the Book of Samuel,* cir. B.C. 1060 : "for the King of Israel is 

 come out to seek a flea." But about seven hundred years later, 

 Aristotle (born B.C. 364), in his History of Animals, shows that 

 he knew the flea underwent a metamorphosis, for he noticed, not 

 only that it had distinct sexes, but also that they produced oKuAtiQ 

 utoaideiQ = egg-shaped worms. I suppose he must be here referring 

 to the pupa, which is egg shaped, for the larva is greatly elongated. 

 He did not, however, trace the changes of the insect far enough, 

 and fancied that the perfect insect was generated spontaneously in 

 the earth f ; and Isodorus, a Bishop of Seville, who lived about 

 the beginning of the seventh century^ stated that the Latin name 

 Pulex was derived ixovo. pulvis — dust, ^^ quasi pulveris filius '^ ; 



* L Samuel xxvi. 20. 

 \ Class, of Ins., Vol. 11., p. 492. 



