PREFACE 



This manual has been written to supply the need which has been felt 

 in this country for a long time of a book containing descriptions of the 

 common invertebrate animals, by means of which their names and affinities 

 can be determined. Excellent general manuals with analytical keys for 

 the identification of the common msects already exist, but a person wishing 

 to identify' animals belonging to most of the other invertebrate groups 

 must usually have recourse to technical papers and treatises which are 

 for the most part inaccessible except to specialists. The book is intended 

 more particularly for use in the eastern and central portions of the United 

 States and Canada, and the endeavor has been made to include in it most 

 of the common invertebrates except insects occurring in this region. In 

 addition to these^ representative species occurring in the western states and 

 on the Pacific slope are included, as are also other species to which some 

 special interest attaches and which are found in other parts of the world. 

 Animals which inhabit the deep sea have not been included except in special 

 cases where they are representative of their particular groups. 



The general plan of the book is similar to that of Leunis' Zoologie, 

 a standard German work which has for two generations supplied the need 

 of a general synopsis of animals in Europe, and has been extensively 

 used elsewhere throughout the world. As in that work, the analytical 

 tables and descriptions of species of each of the larger groups of animals 

 are preceded by a morphological description of the group together with 

 some account of the habits and distribution of the animals. In these 

 descriptions all the technical terms appearing in the tables are explained. 

 References to the principal authorities upon which the descriptions are 

 based are given in footnotes, as are also references to important treatises 

 and monographs which have appeared on the animals described. 



A knowledge of the historical basis of zoological names adds greatly 

 to their significance and the author has consequently given a. history 

 of the nomenclature of each of the larger subdivisions of the animal 

 kingdom in connection with the morphological description of it. A histoi*y 

 of the general dev^elopment of the system of classification since the pub- 

 lication of the tenth edition of Linnaeus' Systema Naturae and a brief 

 survey of the progress of zoological studies in America are added in the 

 Introduction. 



