XVI CONTENTS. 



CHAPTEE XLIV. 



POLYZOA (BRYOZOA, EHRENBERG) ASCIDIAN POLYPES. 



The tangle-thatched reef. Habits of the Polyzoa. Derivation 

 of their name. How to view Polyzoa under the microscope. 

 Mechanism of expansion and retraction. Structure of 

 tentacula. Internal oeconomy. Power of reproduction. 



p. 407-417 



CHAPTER XLV. 



FOLIACEOUS AND INCRUSTING POLYZOA, FLUSTR^, ESCHARJE, 



ETC. 



A delightful walk. Flustrse, or Sea-mats. Escharae. Popu- 

 lation of Flustra membranacea. Structure of Fhtstra hispida. 

 -Reproduction by gemmules. Progressive addition of new 

 cells p. 418-42(3 



CHAPTER XLVI. 



ALCYONIDIUM GELATINOSUM " PUDDING-WEED " 

 "SEA RAGGED-STAFF." 



Philosophy of the sixteenth century. Lord Bacon. Ambrose 

 Pare. Unicorn's horn. Hooke. Theory of pearl-diving. 

 Structure of Alcyonidium gelatinosum. Reproduction by 

 gemmules. Innumerable progeny p. 427-435 



CHAPTER XL VII. 



POLYZOA continued " AVICULARIA ' " VTBRACULA," ETC. 



Suc/ula avicularia. Structure of " avicularium." Probable 

 office of the "Bird's-heads."- -Structure and functions of 

 " vibracula." Distribution of the Polyzoa p. 436-442 



CHAPTER XLVHI. 



TUNICATA ASCIDIANS. 



A stormy day. General description of Ascidians. Forms of 

 simple Ascidians. Organization of simple Ascidians. Re- 



