SCIENTIFIC LITERATURE. 847 



tlie evolution of the liuman intellect. The book as a whole, however, is 

 hio^hly readable, and, with the reserves we have indicated, may be com- 

 mended to those who are interested in the study of sociological questions. 



The Text- Book of Zoology * of Messrs. T. Jeffery Parker and Wtlliam 

 A. Haswell was prepared under peculiar, we might well say unique, condi- 

 tions. Both authors are pi-ofessors of biology at the antipodes, Professor 

 Parker in the University of Otago, New Zealand, and Professor Haswell 

 in the University of Sydney, New South Wales. They have collaborated 

 while being most of the time twelve hundred miles apart by sea, and the 

 manuscripts, proofs, and drawings of the book have had to traverse half of 

 the circumference of the globe, or to London, in their journeys between 

 the authors on the one hand, and the publishers, printers, artists, and en- 

 gravers on the other. Though large and comprehensive, the book has 

 been prepared with strict reference to the needs of the beginner, the mode 

 of treatment being such " that no previous knowledge of zoology is as- 

 sumed, and students of the first and second years should have no more dif- 

 ficulty in following the accounts of the various groups than is incidental 

 to the first study of a complex and unfamiliar subject." Laboratory and 

 museum study is contemplated, and the practice of preceding the study of 

 a given group as a whole by the accurate examination of a suitable mem- 

 Ijer of it is commended. Yet this method of types has its own dangers. 

 "Students are in their way great general izers, and, unless carefully looked 

 after, are quite sure to take the type for the class, and to consider all 

 ai'thropods but crayfishes and cockroaches, and all molluscs but mussels 

 and snails, as non-t^^pical." Hence a zoology that confines itself largely 

 to types as examples "is certain to be a singularly narrow and barren 

 affair, and to leave the student with the vaguest and most erroneous ideas 

 of the animal kingdom as a whole.'' The authors, believing that every 

 group which can not be readily and intelligibly described in terms of some 

 other group should be represented in an elementary course of zoology by 

 an example, have in the majority of cases described in some detail an ex- 

 ample; and in cases where the diversity of organization is very great, two 

 or more examples of every important class. By the time the example has 

 been studied a definition of the class and of its orders will be intelligible, 

 and will serve to show which of the characters already met with are of 

 distinctive importance, and which special to the example itself. To make 

 this part of the teaching more clear, a paragraph giving in more or less of 

 detail the systematic positions of the example, is introduced after the classi- 

 fication. Following the table of classification with its brief definitions, the 

 general account of the group is given, space being allotted to each group, 

 so far as practicable, proportioned to its complexity and range of variation. 

 Following out the plan of deferring the discussion of general principles 

 till the facts with which they are connected have been brought forward, 

 the sections on Distribution, the Philosophy of Zoology, and the History of 

 Zoology have been placed at the end of the book. But, other considera- 

 tions being thought more important in those cases, the general account of 

 the structure and physiology of animals has been inserted immediately 

 after the introduction, and the section on Craniate Vertebrata before the 



♦ A Text-Book of ZoOlogy. By T. Jeffery Parker and William A. Haswell. New York: The Mac- 

 millan Company. Pp. 779 and 08a. Price, $9. 



