31 



teral, closely arranged, bulging at the base, contracted at the 

 neck, with unarmed apertures pointed at the outer martrin, 

 and are situated on the branches and pinnae only. The 

 cells on each internode of the pinnae are crowded together 

 and in contact; but where the internodes join, there is a 

 vacancy, so that they look as if congregated into parallel 

 companies, similar to what occurs in the genus Serialaria. A 

 variety frequently occurs in the distribution of the cells 

 which present the appearance of being arranged in a double 

 row. This is produced by the cells, instead of being arranged 

 in a close straight row, being made to lie alternately on 

 either side of a median line, much in the same way as if 

 the teeth of a saw were bent alternately in opposite 

 directions. The vesicles are pear-shaped, furrowed, with 

 contracted tubular apertures, pedunculated, and irregularly 

 distributed. 



Ellis has given a very good figure of this species, in the 

 centre of the curious frontispiece to his Essay on Corallines. 

 The figure at pi. 7 is not so good either as that, or the one at 

 pi. 38, fig. 6, which he sufficiently explains, by saying it was 

 taken from a dried specimen. Dr. Grant, as quoted by 

 Johnston, represents the terminations of the stems in this 

 species, as being open during growth ; a remark which my 

 opportunities do not enable me to confirm. 



PODDED CORALLINE. P. Cristata. Stem simple, 

 plumous ; pinnae alternate ; cells unilateral, in a close row 

 on the upper side of the pinnas ; apertures large ; margins 

 deeply dentated, with a prominent spine, inferior to the 

 rim ; vesicles barrel-shaped, with serrated ribs. PI. viii. 



The Podded Coralliae, Ellis' Coral., p. 13, no. 12, pi. 7, 

 fig. b B. Sertularia pluma, Ellis and Solander's Zooph., p. 

 43. Turton's Lin., vol. 4, p. 679. Stewart's Elem., vol. 2, 

 p. 443. Aglaophenia pluma, Lamouroux's Coral., Flex., 

 p. 170. Plumularia pluma, Fleming's Brit. An., p. 346. 

 Plumulata cristata, Templeton in Mag. Nat. Hist., vol. 9, 

 p. 467. Johnston's Brit. Zooph., p. 143, pi. 19, figs, and 3, 

 pi. 20, fig. 1. 



Hab. On Ascidia, Fuci, Pinna ingens, oysters, stones, 

 from one to fifty fathonis of water, very common. Polperro, 

 Looe, Seaton, Goran, Port Loe, &c. 



This common and delicate species is attached to the sub- 

 stances on which it grows by means of brown, creeping, 

 tubular fibres, which trail irregularly in all directions, and 

 send off plumous shoots from one to three and half inches 

 high, irregularly throughout its course. The stem is polish- 

 ed, jointed, of a dark brown, and frequently almost of a black 



