FUj. 40. 



JV. ZOOPHYTA ASCIDIOIDA. 



FAMILY IX. VESICULARIADJS. 



Since we profess to be guided, in the classification of zoophytes, by simi- 

 larity in the structure of the polypes considered independently of their poly, 

 pidoms, the Vesiciilariadje, notwithstanding their apparent dissimilarity, must be 

 associated in the same order N\ith Alcyonidium and Flustra. They have been 

 hitherto united with the Sertulariadee, and previous to our knowledge of their 

 polypes, this seemed a very natural union, for the polypidoms of both are slen- 

 der and plant-like, horny, fistular and flexible, and furnished with somewhat si- 

 milar cells on their branches. But the differences between them even in out- 

 ward aspect are not inconsiderable, and although it may be difficult to point out 

 these by any description, they are nevertheless not the less obvious to one fa- 

 miliar with the objects. The polypidoms of the Vesiculariadae are more flexible 

 and of a thinner texture, less arboreal and more confervoid, not so regularly 

 jointed, nor ramified in the same determinate and fixed manner. They are all 

 marine productions, generally not more than an inch or two high, and are found 

 attached only to sea-weeds or other corallines. 



For a knowledge of the animated tenants of these structures we are indebted 

 to Cavolini, the Rev. Dr Fleming, J. V. Thompson, Esq. and more particularly 

 to Dr F'arre, of whose researches a summary has been given in the preliminary 

 observations. The following is his description of the cells in the present fa- 

 mily : 



" The transparent horny cell which closely embraces the body of the animal 

 is nearly unyielding in its lower two-thirds, but terminates above by a flexible 

 portion, which serves to protect the upper part of the body when the whole is 



