The Presence of Two Spermathecce in the Bare Mole Flea. 247 



my friend Mr. Bacot, of the Lister Institute, and in all I have 

 found that two spermatheccB were present. As the shape of the 

 spermatheca varies in different species of the Siphonaptera, and 

 has sometimes been used as a point of distinction, it seems curious 

 that the presence of a pair should apparently have escaped notice. 



A point of considerable biological interest in connexion with 

 H. talpse, which also seems hitherto unrecorded, is that this flea 

 occasionally acts as host for the hypopial nymphs of one of the 

 Tyroghj-phidse. One of my specimens has a number clinging to 

 the abdomen. There are three or four genera of these minute 

 mites which infest bees, and also at least three that are found on 

 the mole. Michael has described the complete life-history of two 

 out of the three found on the mole, but the hypopial nymphs do 

 not resemble those seen on this Ilea. Indeed, I have been unable to 

 find a figure or description in either Michael or Bank's works that 

 quite resembles these specimens, though I think they are near some 

 of the genera found in the nests of bees, perhaps near Ghjcyphagus 

 dispar. 



As the hypopial nymph is the stage in the life-history of the 

 TjjroglyphidR', at which they are dispersed abroad, it is probable 

 that H. talpx acts as the natural distributor for this species, for not 

 only has this flea been taken in the nests of bumble bees, as well 

 as upon its regular hosts the mole a^d field vole, but the vole is a 

 regular visitor to and robber of the bees' nests. The larvse and 

 ordinary nymphs of these Tyroglyphid mites generally resemble 

 the adult in appearance, but hypopial or travelling nymphs often 

 exist, and these are quite different, having well-developed al)doniinal 

 suckers by means of which they cling to their temporary host. 

 They cannot be termed true parasites at this stage of their life- 

 history, for they are incapable of absorbing nourishment, the mouth- 

 parts not being fully developed. 



J. G. Tatem, in the Monthly Microscopical Journal for 1872, 

 mentions having found a mite on a flea, but does not state if the 

 flea was found on a mammal or a bird, nor does he give any 

 description of the mite, though proposing the name Acarcllus 

 p^dicis for it. His rough drawing is obviously that of the hypopial 

 stage of a Tyroglyphid. 



BiBLIOGKAPHY. 



Curtis. — British Entomology, vii. p. 114 (1826). 



Walkek. — Insecta Britannica, Diptera III., p. 4 (1851-6). 



Taschenberg.— Die Flohe, p. 83 (1880). 



Baker.— Eevision of American Siphonaptera, in Proc. U.S. National Mus., 



xxvii. (1904), pp. 364-469; xxix. (1905), pp. 121-70. 



Canadian Entomologist, xxvii. (1905), p. 186, 



Rothschild. — Entomologist's Eecorcl and Journ. of Variation, xii. (1900), 



p. 257. 



