368 POLYZOA INFUNDIBULATA. 



they are nevertheless not the less obvious to one familiar with the 

 objects. The polypidoms of the Vesiculariadoe are more flexible and 

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

 larly jointed, nor ramified in the same determinate and fixed man- 

 ner. 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. Farre,* of whose researches a sum- 

 mary has been given in the preliminary observations. The following 

 is his description of the cells in the present family : — 



" 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 expanded, in which state it is of the 

 same diameter as the rest of the cell ; but when the animal retracts 

 is folded up and drawn in after it, and completely closes the mouth 

 of the cell. 



" The flexible part consists of two portions, the lower half "being a 

 simple continuation of the rest of the cell ; the upper consisting of a 

 row of delicate bristle-shaped processes or setoe, which are arranged 

 parallel with each other round the top of the cell, and are prevented 

 separating beyond a certain distance by a membrane of excessive 

 tenuity, which surrounds and connects the whole. This mode of 

 termination of the cell is one of constant occurrence, as will be 

 described in other species, and is evidently a provision for allowing 

 of the freest possible motion of the upper part of the body in its 

 expanded state, to which it affords at the same time support and 

 protection." Phil. Trans, an. 1837, p. 393. 



23. SERiALARiA,-f- Laiiiarck. 



Character. — Polyp'idom confervoid^ Uoniy^ the shoots slen- 

 der, filiform, fisttilar, and hranched ; cells tubulous, uniserial 

 and unilateral^ disposed in close parallel companies at stated 

 intervals ; polypes ascidian. 



\ . S. LENDiGERA, mucA branched, the branches spreading, 



* To these I have now to add Van Beneden, Hassall, and Professor John Reid. 

 t From seriala, a diminutive formed from scrks, a row. 



