THIS little book, long out )f print, is now offered by us tc 

 teachers as one of our " SCIENCE GUIDES," because it 

 fits very appropriately into the series. With admirable 

 clearness and brevity, it gives in narrative form for young 

 children a general history of Hydroids, Corals, and 

 Echinoderms ; thus rendering unnecessary a part of the 

 work we had proposed to ourselves in connection with our 

 late lectures on this subject. It will be found, we think, 

 of great service where this kind of teaching is needed, 

 and has saved us much trouble and expense in the prep- 

 aration of the supplementary guide which is to follow. 



For the use of the wood-cuts we are indebted to Mr. 

 Alexander Agassiz. It is one of many favors received at 

 the hands of the family of the late Professor Agassiz, as 

 well as from others ; all of which it will be a pleasant 

 duty to acknowledge at some future time. 



ALPHEUS HYATT. 



