HYDEALLMANIA FALCATA. 273 



Hob. On stones &c. from deep water, rare ; this is an 

 exclusively northern form. Coast of Aberdeenshire (R. 

 Brown): Northumberland, at Dunstanborough (R. Em- 

 bleton): Cullercoats, and from the five-men boats (J. A.): 

 Whitburn, Durham (Miss M. Dale) : off Holy Island (New- 

 castle Dreclging-Committee) : Stonehaven (Lady Keith 

 Murray) : off Staples in 35 fath., and off Buchanness 

 (Lieut. Thomas): Peterhead, very fine, but not common 

 (C. W. P.): Scarborough (W. B.): Filey (T. H.). 



Genus HYDRALLMANIA*, Hincks. 



Der. Named in honour of Prof. Allman. 



GENERIC CHARACTER. Zoojjhytefjlant-like; stem bearing 

 plumous branches, jointed, rooted by a filiform stolon ; hy- 

 drotheca unilateral, arranged in distinct companies, each of 

 which occupies an internode ; gonothecas scattered, with a 

 simple, inoperculate aperture. 



H. FALCATA, the type of this genus, was referred to Plu- 

 mularia by Johnston, on account of the unilateral arrange- 

 ment of the calycles ; but its affinities are with the Sertu- 

 lariidse, and not with the Plumulariidse : from the latter 

 group it is separated by the absence of nematophores. 



H. FALCATA, Linnseus. 



" SICKLE CORALLINE," Ellis, Corall. 12, pi. vii. figs, a, A, and pi. xxxviii. fig. G. 

 SERTULARIA FALCATA, Linn. Syst. 1309; Pall. Elench. 144; Esper, Pflanz. 



Sert. t. ii. figs. 1, 2. 

 AGLAOPHKNIA FALCATA, Lamx. Cor. flex. 174. 



* I ha-ve adopted this form for the generic name, simply because Allmania 

 has been already appropriated to a genus of plants, in honour of another 

 naturalist. 



