Chapter I 



LIST OF LAND AND FRESHWATER ANIMAL SPECIES 

 COMMON TO EUROPE AND NORTH AMERICA 



Introduction 



This list is pronouncedly selective. It was necessary to restrict its content to 

 animal groups sufficiently known with regard to taxonomy and distribution. In 

 spite of this limited scope the groups considered are by no means equally well 

 suited for the purpose. In some, as in birds, Carabid beetles, and certain Lepido- 

 ptera, specialists have made direct and careful comparisons between Old and New 

 World forms, in others a modern revision is still needed and compilations had to 

 be made from the often rather routine-stamped records of catalogues or from scat- 

 tered revisions of smaller taxonomic units. I am fully aware that, owing to the 

 extensiveness of the task, parts of the purely taxonomic literature have been 

 overlooked, which is much regretted. Also, introduced species which have appeared 

 more or less sporadically in either or both continents, for instance in hothouses, 

 have certainly not been listed in full. 



It is also evident that the species and subspecies concepts are not used identically 

 in different groups of animals and direct comparisons of the zoogeographical signi- 

 ficance of, for instance, a bird and an insect subspecies should be avoided. The 

 criterion of a species seems to be especially obscure among mammals so that 

 "species" of that group apparently often correspond to what is called "subspecies" 

 in others. 



Genera and species, under each higher taxonomical unit, are listed in alphabetical 

 order. Names in brackets are synonyms. Subgeneric names have not been used. 



Names in English, according to both American and European practice, if 

 different, are added for vertebrates only. 



The records of distribution are quite summary. Their main purpose is to show 

 whether the species, in Eurasia as well as in America, is transcontinental or not. 

 More detailed records, for instance of the occurrence in the British Isles, are particu- 

 larly given within groups containing species which are introduced into North 

 America. Subspecies, if any, are listed in geographical order: if numerous sub- 

 species are described from a limited are, only their approximate number is given. 

 Subspecies outside the actual area are omitted. 



