Vill INTRODUCTION. 
across into the Old World, where it is represented by the Camels, and into South 
America with the Llamas as representatives. The genera, however, of the Anyphenide 
still exist in the region of their origin, while those of the Camelide have died out. 
These few instances must suffice for the present, but they will serve to indicate 
the various sources whence the Spider-fauna of Central America may have been 
derived. 
The scheme of classification presented in the following pages does not differ 
materially from that usually adopted, except as regards the position of the Thomiside 
and Salticide. These families are here assumed to be allied to the Clubionide, and 
not linked with the Argyopide and Lycoside respectively, as previously placed by 
Authors. 
The systematic position of the Cribellate is still one of the unsolved problems of 
Araneology. In the list of families drawn up in the Synoptic Table on pp. 541-544, 
the arrangement has been somewhat modified from that followed in the previously 
published text, as it was impossible to prepare this till the whole of the material had 
been studied. 
As regards the actual identification of species, always a matter of great difficulty, we 
have fortunately had access to the types in the collection of the late Count Keyserling 
in the British Museum of Natural History. With these for reference, it has been 
possible to determine with some confidence a great many American forms. 
In the “ List of Identified Species,” given by the Rev. O. Pickard-Cambridge in the 
_ Introduction to Vol. L., pp. xiii-xv, there are various names which will not be found 
quoted in the present volume. This apparent omission is due to difference of opinion 
as to the identification of the forms involved, or at least as regards those contained in 
the Godman and Salvin Collection. 
The Opiliones, or Harvestmen, do not call for any special comment, and remarks 
on their geographical distribution, &c., are to be found on pp. 546-548. Nearly 
all the species (70) enumerated are treated as new, these Arachnids having been 
much neglected by zoologists. 
The collections amassed by the Editors of this work have been mainly contributed 
