324 ARACHNOIDEA. 



CASE never seen any of the species, and merely hazard its location here 

 ^^' as a probable conjecture. He has described six species, and 

 we copy his figures of two of them. The bristles or hairs are 

 somewhat pecuHar, varying in each species, but apparently of the 

 same type in all. From the figures the texture of the skin would 

 appear to be transversely striated as in the preceding genus, 

 although this is not specially mentioned by Kolenati. 



Peplonyssus seminulum {Kolenati, Sitz. Akad. Wissen. Wien, 1858, p. 75)-. 

 Yellowish brown. From the ears and skin of Nycteris thebaica^ 

 in Egypt. 



P.plonyssus seminulum. Copied from ^"P^°"^'''"' S'lTati ^"P'^'^^'^^"* 



Kolenati. o-oo2 Parisian metres in length. ^.^^^3 p^^.^.^^ .^^j^^^ j^ ^^^^^^^ 



Peplonyssus pagurus {Kolen., loc. cit. p. 78), 



Yellowish brown. On Rhinopoma microphyllum, GeofFr., iii 

 Egypt. 



Genus Listrophorus {Pagenstecher). 



The Listrophori are another type of parasitic mites found upon 

 small mammals. Claparede speaks as if they were confined to the 

 rodents such as field mice, but it would appear not to be wholly so. 

 We have specimens of Listrophorus gibbus from the ferret, and 

 another species from the polecat ; and seeing that these beasts of 

 prey must often feed on field mice, it is not very difficult to imagine 

 that they may more or less frequently be invaded by their parasites. 



This genus furnishes a scarcely less remarkable instance of 

 modification of structure to purpose than Myobia. In Listro- 

 phorus the maxillae are transformed into two flexible shovels or 



