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F. CARNOSA. Encrusting; fleshy, with imbedded remote 

 cells; apertures contracted and armed. 



Flustra hispida, Fleming's Brit. An., p. 537. Flustra 

 carcosa, Johnston's Brit. Zooph., p. 288, pi. 37, fig. 5. 



Hab. On Fuci, common. 



It is a thick, fleshy encrusting species, of a light brown or 

 cream colour. The cells are imbedded, distant from each 

 other, with contracted wrinkled apertures of a half-moon- 

 shape, and three or four erect spinous teeth. 



F. TUBERCULATA. Encrusting, calcareous, thin ; cells 

 oval, with a tubercle on the distal, and one on each lateral 

 margin. 



Flustra tuberculata, Johnston's Brit. Zooph., p. 289, pi. 

 34, fig. 9. 



Hab. On stones a few miles from the shore. Polperro. 

 Goran. Mount's bay. 



This is not a rare species, but is to be found encrusting 

 stones at short distances from the shore, from the entrance 

 of Plymouth sound to Falmouth harbour and Mount's bay. 

 In a living state it is so much unlike the figures and des- 

 criptions given of it, that at one time I considered it a new 

 species, and it was by an examination of the dried specimens 

 only that the mistake was discovered. In a living state, 

 its encrusting character resembles the Flustra membranacea, 

 being thin and gauze-like; but it encrusts stones instead of 

 sea weed. It is most commonly found in circumscribed 

 patches varying from a quarter to one inch in diameter. 

 The cells are alternate with stout calcareous rims, and 

 are oval, inclining to a quadrangular or lozenge-shape. At 

 each angle is a large stout tubercle, without any spine or 

 process. It is of a deep flesh red colour. As the cells 

 are alternate, with a tubercle on the distal margin, each 

 appears to be surrounded with four, which slightly encroach 

 on the quadrangular diameter. These tubercles are always 

 of a brighter colour than any other part. 



When the specimen is dried, this appearance is consider- 

 ably altered ; the quadrangular shape of the cells is changed 

 into an oval ; the tubercle on the distal margin appears 

 to be considerably above the cell and to stand on a hollow 

 dome; and on each side is a curved process. This species 

 assumes a great variety of forms, from the appearance of 

 this tubercle. In old specimens it is so much injured, and 

 sometimes so entirely destroyed, that it is difficult to re- 

 cognize it; in these states Dr. Johnston's figures represent it, 



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