xix BRITISH MARINE GENERA 5 33 



Main stem zigzag. Branchlets delicate, many ending in sharp points. 



Zooecia small, ovoid . . . Vesicularia spinosa 



Axis jointed. ' Zooecia small, in small clusters. Polypide without a 



gizzard .... Valkeria uva, var. cuscuta 

 Zooecia in whorls, attached to the axis by thread-like stalks, much 



longer than themselves . . Ifippuraria egertoni 



78. 



79. 



80 



83 



( Zooecia pear-shaped, produced at the lower end into a distinct stalk. 

 Gizzard absent . . . . . .80 



\ Zooecia not distinctly stalked, although sometimes constricted at the 

 ( base . . . . . . .81 



Stalk long. Zooecium movable on its stalk, compressed, with a 

 membranous area on one side. Twelve or more tentacles. 

 Usually found on Crustacea . . . TriticeUa 



Stalk variable. Zooecium very transparent ; orifice bilabiate. Ten 

 to sixteen tentacles . . . Farrella repens 



Zooecium very small, much elongated and narrow. Eight tentacles. 



Valkeria tretn/ula 



(See also Arachnidium, No. 73). 



[ Zooecia short, minute, with a few short spines on each side of its 



81. -J broadened base. Upper end tubular . Buskia nitons 



I Zooecia elongated . . . . . .82 



f Zooecia transparent . . . . . .84 



( Zooecia brown, often quite opaque . . . .83 



C Zooecia large (about -fa inch long), distant, constricted at the base, 

 bearing scattered bristles. Usually found on Crabs or Hydroids. 



Avenella fusca 

 Zooecia tall, cylindrical, not constricted at the base . Gylindroecium 



Zooecia minute. Axis dilating at intervals into swellings, from 

 which new zooecia originate. These may give rise to new stolons, 

 or directly to new zooecia. No gizzard. Found in brackish or 



I fresh water .... Victorella pavida 



Axis not dilated, as above . . . . .85 



C Zooecia small, in small groups. No gizzard . . Valkeria wva 



85. -J Zooecia long, scattered or in groups. Gizzard present. 



Boiverbankia (creeping forms) 



It is highly probable that the Ctenostome genus Hypophorella l 

 will before long be added to the British Fauna. The animal 

 consists of delicate stolons, which give off small zooecia at 

 intervals ; and it is known to excavate passages in the substance 

 of the tubes of certain Polychaet worms (Chaetopterus and 

 Laniee). 



1 See Arch. Zool. Exp. 2 ser. vi. 1888, p. 135 (as Delagia), and ibid. x. 1892, 

 p. 594. [See also J. Mar. Biol. Ass. v., 1897-99, p. 51.] 



i 



