SALACIA. 211 



and half-membranous continuation of the walls of the 

 hydrotheca, and is crowned by a very beautiful operculum, 

 which is capable, as in several allied forms, of being re- 

 tracted within the cylinder. The transverse rings or ribs 

 mark the periods of growth. The present species is very 

 minute. 



Hab. On Syncoryne eximia, Whitby, Yorkshire (T. H.). 



Genus SALACIA, Lamouroux* . 



GRAMMARIA, Stimpson, Marine Invertebrate of Grand Manan, 9. 



GENERIC CHARACTER. Stem erect, composed of aggre- 

 gated tubes, branching, rooted by a filiform stolon (?); hy- 

 drotheca cylindrical, sessile, without operculum, adnate for 

 the greater part of their length, disposed on all sides of the 

 stem and branches in regular and equidistant longitudinal 

 series ; gonothecce scattered on the stem and branches ; 

 gonophores unknown. 



Polypites long, cylindrical, with a conical proboscis. 



THE Salacia of Lamouroux, founded on an Australian 

 Hydroid (S. tetracyttara], is identical in all essential par- 

 ticulars with the Grammaria of Stimpson, and I have 

 therefore restored his name. In Lamouroux's species the 

 stem is much compressed, and the apertures of the hydro- 

 thecae are on a level and scarcely project, but in other 

 respects it closely resembles the American and British 

 form. 



Salacia is very nearly related to Lafoea. The principal 

 difference between them is to be found in the disposition 

 of the calycles : in the latter genus they are irregularly 

 distributed ; while in the former they are arranged on a 



* Polypes Flex. Corallig. p. 214; Exposition Methodique. p. 1.~>. 



