ESCIIARIDiE : FLUSTRA. 349 



smooth septa ; the aperture small, semilunar, with an even rim. 

 E. Forbes. 



Plate LVI. Fig. 8. 



Flustra coriacea, Esper Pflanz. Flust. Tab. vii. fig. 2. 



Hab. Encrusting old shells. On Pecten opercularis, Isle of Man, 

 U. Forbes. On stones from Fowey harbour, C. W. Peach. On shells 

 dredged off Sana Island by G. C. Hyndman. 



This species forms a thin greyish-white crust, closely adherent to 

 its base, and about the size of a sixpence but capable of enlargement 

 to an indefinite extent, with the cells large enough to be visible to 

 the naked eye : the cells are broadly elliptical but the figure en- 

 croached upon behind, contiguous, quincuncial, coriaceous, the walls 

 smooth when wetted, when dried they were somewhat granulous and 

 sunk, the septa smooth and a little raised, the aperture small, sub- 

 terminal, semilunar, (the upper or proximal margin being straight 

 and transverse,) surrounded with a plain even rim. On most of the 

 cells there are two hollow tubercles at the aperture, one on each of 

 its posterior angles. 



The figure of Esper is a very good one, but he represents the aper- 

 ture as being circular, Avhich was not the case in our specimens. 



10. F. ? LiNEATA, cells oval^ separate, the margin hispid toith 

 a series of short spines, erect or bent inward. Professor 

 Jameson. 



Plate LXVI. Fig. 4. 



Flustra lineata, Lin. Syst. 1301. Mull. Zool. Dan. prod. 253. Fabric. Faun. Groenl. 

 437- .Jameson in Wern. Mem. i. 563. Couch Zooph. Cornw. 55 : Corn. Faun, 

 iii. 124. W. Thompson in Ann. Nat. Hist. v. 253. — Flustra spinifera, Johnston in 

 Trans. Newc. See. ii. 26G, pi. 9, fig. 6. — Fl. hirta, Lamour. Corall. 49. Bosc Vers, 

 iii. 144. Risso L'Europ. Merid. v. 334. 



Hah. On rocks, old shells, and on sea-weeds near low-water mark, 

 common. 



Polypidom membranous, closely-adherent, spreading irregularly, 

 sometimes in circular patches, of a horny texture and yellowish- 

 brown colour ; the cells just visible to the naked eye, more or less 

 contiguous, oval or oblong, the margins ciliated with short spines 

 that bend across the open upper surface. There is often a small 

 pearly ovarian capsule over the aperture. 



LinnfBus has described this species well, and his description is 

 rendered complete by Otho Fabricius, who correctly says, — " Impres- 



