Fig . 46. 
FAMILY XIII. ESCHARIDiE. 
35. Flustra,* Linnaeus. 
Character. Polypidom plant-like, membranaceous , flexile , 
frondose or crustaceous, formed of cells arranged quincuncially in 
several series and in one or two layers : cells in juxtaposition , 
more or less quadrangular , flat , with a distinct border ; the 
aperture transverse , semilunar , valvular , subterminal.-f — Po/y- 
ascidian. 
* Foliaceous, with cells on both sides. 
1. F. foliacea, cells narrow at the proximal and arched at 
the distal extremity , with scattered marginal denticles. 
Plate xxxv. Fig-. 1, 2. 
Fucus marinus scruposus albidus telam sericeam textura sua aemulans, Mor- 
ris. Hist. Plant, iii. 646, tab. 8, fig. 16. (bona.) Fucus telam lineam 
sericeamve textura sua aemulans, Haii, Syn. 42, no. 9. Jussieu in Mem. 
Acad. Roy. des. Sc. 1742, 298, pi. 10, fig. 3 Broad-leaved Horn- 
wrack, Ellis, Corail. 70, no. 2. pi. 29, fig. a, A. B, b Curious sea- 
weed, Hooke, Microg. 140, pi. 9, fig. 2; and pi. 14, fig. 1 Eschara 
foliacea, Lin. Syst. edit. 10, 804. Pall. Elench. 52 Flustra folia- 
cea, Lin. Syst. 1300. Mull. Zool. Dan. prod. 253. Fabric. Faun. 
Groenl. 436. Ellis and Soland. Zoopb. 12, pi. 2, fig. 8. Berk. Syn. i. 
214. Turt. Gmel. iv. 663. Wern. Mem. i. 563. Turt. Brit. Faun. 
* From the Saxon Flustrian, to weave : hence Flustra applied by Linnaeus 
to these sea-mats. 
f “ The aperture of the cells is formed by a simicircular lid, convex exter- 
nally and concave internally, which folds down when the polypus is about to 
advance from the cell. The opening of this lid in the F. truncata, where it is 
very long, appears through the microscope like the opening of a snake’s jaws, 
and the organs by which this motion is effected are not perceptible. The lid 
of the cells opens and shuts in Flustrae, without the slightest perceptible 
synchronous motion of the Polypi.” Grant in Edin. New Phil. Journ. iii. 339. 
