viii PREFACE. 



preparation or specimen should precede that of the 

 accounts in the introduction of the Class and Sub- 

 kingdom to which it belongs, and that the study of 

 the Descriptions of the Plates should be taken up only 

 after the attainment of a considerable familiarity with 

 actual specimens by the practice of dissection. 



A short statement of the method which has been 

 adopted in the preparation of each specimen has in 

 most cases been prefixed to the description of it ; and 

 thus persons who have not, as well as those who have, 

 access to the series in the University Museum, are en- 

 abled to reproduce for themselves the objects described. 

 The specimens themselves, it will be observed, are in 

 the great majority of instances taken from animals 

 which may be found living in inland parts of this 

 country; and even when they have been taken from 

 an exclusively marine Class or Sub-kingdom, such as 

 the Tunicata or the Echinodermata, they are, with an 

 excei)tion or two, readily procurable in places at a 

 distance from the sea-coast a. 



Small print has been employed in the notes and in 

 other passages, which the student may do well to omit 

 when first reading this book. 



In some cases, even the beginner will find it necessary 



a A dissecting microscope will be required for the verification of the 

 Descriptions of many of the Preparations of the Invertebi-ata, and in 

 these cases the specimens should be affixed to a loaded cork or wax 

 tablet, and dissected under water or spirit. Some of these animals are 

 speedily killed by being placed in a glass-stoppered bottle with a few 

 drops of chloroform 3 others by immersion in water several degi'ees 

 below i40°F. 



