Vlll. 



INTRODUCTION. 



very closely allied forms ; but the printed tablet may explain 

 the circumstances under which they occupy their position, 

 and render the disadvantage simply a negative one, namely, 

 that in such instances the arrangement cannot afford much 

 help to the memory. It is, on the other hand, one of the 

 peculiar advantages of the plan that the tray or drawer con- 

 taining an entire group can, with the utmost facility, be 

 removed to be re-arranged, to illustrate a lecture, or to 

 occupy a different position in the series. 



Plan of a Group on a scale of ith tin. 



In the present unsatisfactory condition of systematic 

 Zoology, probably the only thoroughly scientific mode of con- 

 veying information respecting an assemblage of organic forms 



