270 NATURAL HISTORY OF 



Hab. : Generally distributed. 



The cells are ovate, very small, and of a pearly-white 

 colour, extended below to a slender thread which con- 

 nects each cell with the one next to it. It has been 

 called by Mr. Couch, " the Smaller Beaded Coralline." 

 The branching takes place in a single series at right 

 angles to the cells, and in every case commences from 

 the centre of a cell. In one variety, however, to which 

 the name " conferta" has been given, the cells are 

 crowded together, and are not arranged in single series. 

 This variety appears to be found always on seaweeds. 



The cells are sometimes smooth, and at other times 

 more or less distinctly crossed by transverse markings, 

 and in the variety conferta there is a boss below the 

 orifice of each cell. 



2. H. EXPANSA, Dawson. 

 Hab.: Off Unst (C. W. P.). 



The cells are larger than in the preceding species, 

 and are regularly transversely striated. H. expansa is 

 a deep-water species, and is a native of the northern 

 seas. 



3. H. DiSTANS, MacGillivray. 

 H. flagellum (Manzoni, Hincks). 

 Hab. : Generally distributed. 



The cells in this species are smaller than in H. 

 divaricata. The species are also distinguishable by 

 the shape of the orifice, that of the present being egg- 

 shaped, whilst that of divaricata is semicircular, with a 

 notch in the lower margin. The colonies of this 

 species have a perfectly dendritic mode of growth, in 

 single series, and the tubular expansions of the cells 

 are very long. 



This species is described by Mr. Hincks (B. M. P., 



