128 



BIRD'S-HEAD CORALLINE. C. Avienlaria. Calca- 

 reous, erect, dichotomouslv branched ; cells glandular, 

 opening on one plane, with an erect spine at each superior 

 angle, and the rudiments of two others below, crossing the 

 diameter. 



Bird's-head Coralline, Ellis's Coral., p. 36, pi, 20, fig;, a 

 A. Sertularia avicularia, Turton's Lin., vol. 4, p. 685. 

 Stewart's Elem., vol. 2, p. 448. Cellaria avicularia, Ellis 

 and Solander's Zooph., p. 22. Crisia avicularia, Lamou- 

 roux's Cor. Flex., p. 141. Templeton in Mag. Nat. Hist., 

 vol. 9, p. 4G0. Cellularia avicularia, Johnston's Brit. Zooph., 

 p. 292, pi. ao, fig. 78. 



Ifab. On the back of the Corwich crab ; at low water 

 mark. Mevagissey bay. Mount's bay. 



This beautiful and delicate coralline is by no means com- 

 mon ; compared with the others of this genus, it is more 

 bushy, erect, and graceful. It is calcareous, erect, dicho- 

 tomously branched, and varies in height from one inch, 

 to one and three quarters. When living it is very elastic 

 and of a delicate flesh colour ; but when dead, it is white and 

 brittle. It is rooted by matted tubular fibres, and it arises by 

 a small round stem, which soon begins to divide and branch. 

 The branches are formed of two rows of alternating cells 

 which open on one plane. The cells are quadrangular 

 and have a spine at each superior angle which point up- 

 wards; below these are two others, one on each side, which 

 cross the diameter of the cell; these last are souietimes 

 absent or in so rudimentary a state as scarcely to be noted. 

 The apertures, like those of Flustra, are subterminal and 

 transverse, and are covered with pearly shield-like opercuhi, 

 which become elevated between the superior spines in dying. 

 On the external edges of the cells, there are frequently 

 appendages, resembling birds heads, to be seen, which move 

 to and from with the regularity of a pendulum, at the same 

 time they open and shut their bills like a bird. Tiiis species 

 has been considered the young state of Flustra avicularis by 

 some authors, but irom this 1 dissent, and the reasons for 

 which are briefly noticed under I'lustra avicularis. 



CELLULARIA PLUMOSA. Confervoid ; cells biserial, 

 alternate, opening on one plane; apertures irregularly 

 elliptical, with a stout spine on the outer and upper margin. 

 PI. xxiii., fig. 4. 



Corallina pumila erecla ramosior, Raii, Synop., vol, 1, 

 p. a7, pi, 2, fig.l. Solt Feathered Coralline, Ellis' Coral., 

 p. 33, pi. 18, lig. a A. Seitidaria fastigiata, Turton's Lin., 

 vol. 4, p. 684. Stewart's Ekui., vol. 2, p. 448, Cellularia 



