176 ARACHNOIDEA. 



CASE being due to affinity, but the teleologist may perhaps say that it 

 indicates that there is some condition of hfe shared by both, 

 which makes it necessary or advantageous for the animals exposed 

 to it to be so provided. 



The genus Caris of Latreille was established upon the six-footed 

 young of the Pteropti, and the names Celeripes and Spinturnia, 

 given respectively by Montagu and Heyden, are synonyms of 

 Pteroptus. 



Kolenati has paid much attention to this group, and has pub- 

 lished important contributions to our knowledge of its species in 

 various works, of which the more important are " Die parasiten 

 der Chiroptern," his "Bietrage zur Kentniss der Arachniden," 

 pubHshed in the "Sitzungs. Akad. Wissenchaft Wien," and 

 various papers in other scientific journals, such as the "Wiener 

 Entom. Zeitschn," the " Stettiner Entom. Zeitung," the " Bulletin 

 of Imp. Acad. Nat. Moscow," &c. In these he has described 

 and figured many species and established so many new genera, 

 that he found it necessary to make a separate family for the 

 group (Pteroptidae). We have thought a sub-family sufficient. 

 His two most important new genera are no doubt rightly put 

 apart — indeed we do not think that either of them belong to the 

 Pteroptidae at all — but the rest of his genera seem all very close 

 to each other, and, although we note and figure them, it is for the 

 reader's information, not because we believe them to be good 

 genera. 



The two genera (Otonyssus and Peplonyssus) which differ in 

 a marked manner from the species among which Kolenati places 

 them, are only six-footed, and therefore probably the young of 

 some eight-footed species. The natural supposition would be 

 that, being parasitic upon bats, they are the young form of some 

 Acaroid parasite of that class of animals — such as Dermanyssus, 

 Pteroptus, or Ixodes — and Pteroptus being, par excellmce, the 

 bat parasite, it is most natural that it should be the genus looked 

 to. But there are such material differences here, and equally 



