526 



Genus AVENELLA, Dalyell. 



Der. Dim. of avena, oats. 

 AVENELLA, Dalyell, Rom. An. Scotland : Wyville Thomson. 



GENERIC CHARACTER. ZCKECIA solitary, irregularly 

 scattered, subunilateral, curved, and slightly contracted 

 above. STEM repent, nearly simple. POLYPIDES with 

 numerous tentacles and a small gizzard. 



THERE has been some strange misapprehension amongst 

 authors respecting this well-marked form. Notwith- 

 standing the figures and excellent descriptions of it which 

 we have from Sir J. G. Dalyell and Sir Wyville Thomson, 

 it has been perseveringly identified by several of our recent 

 writers on the Polyzoa with the Cylindr cerium dilatatum 

 of the present work, a species with which it has little in 

 common. Indeed the two forms belong to different fami- 

 lies. Avenella is furnished with distinct, deciduous cells ; 

 whilst the species with which it has been confounded has 

 its cylindrical zooecia closely and permanently united to 

 the creeping stem. 



It is somewhat remarkable that a form which Sir Wy- 

 ville Thomson describes as " one of the largest and most 

 conspicuous of our Vesicularian Polyzoa," and which 

 seems to be abundant on certain parts of the coast, should 

 have attracted hitherto so little attentipn and been so 

 generally misunderstood. 



Avenella is separated from the other members of the 

 family by the peculiarities of its cell and its large number 

 of tentacles. 



