Natural History. 418 



ly afterwards, if many white or yellow planiilfie occupied a vessel, a 

 number of white or yellow spots, circular or spherical segments, and 

 of about what might be grossly computed of equal superficial area to 

 planulse, may be discovered in nearly the same place. Next, the sum- 

 mit of the segment rises in an obtuse spinous prolongation, which, 

 swelling into a cell as it advances, soon displays a living polypus in 

 full vigour. Other cells are formed by further extension of the 

 stalk, and by the divergence of the buds which constitute them, to 

 right and left. Meantime the original spot breaks into divisions 

 like radicles ; it is gradually attenuated, and at last disappears. The 

 first animal is quite as large as any of those succeeding it in the 

 growing product ; but probably the figure of later cells of some 

 species undergo modifications. Plantations of hundreds of Sertu- 

 lariffl may be easily obtained. According as the dying planula is 

 white or yellow, so is the circular root invariably white or yellow. 

 Although some important obscurities remain for elucidation, I have 

 been hitherto unable to recognise any other elements of the nascent 

 Sertularia. 



5. The Flustra Carhasca resembles a leaf divided into subordi- 

 nate parts, one of the surfaces being studded with cells, and the 

 other exhibiting elevations or convexities corresponding to their 

 bottom ; and the whole product is of a yellowish colour. Each cell, 

 of a shuttle or slipper shape, level with the surface of the leaf, is 

 inhabited by a vivacious polypus, exercising a percussive faculty 

 both of the tentacula individually, and of the whole head. Some of 

 the cells are occupied occasionally by large, bright yellow, irregu- 

 larly globular, solid ciliated animalcula, subsequently quitting them 

 to swim heavily below. In several days they become motionless 

 like the former, and die also without immediate decomposition. 

 Next, there appears in just about the same spot below occupied by 

 the motionless animalculum, a yellow nucleus with a lighter diffu- 

 sing margin. This in its farther diffusion assumes a shuttle or slip- 

 per form ; it becomes a single cell, which afterwards displays a po- 

 lypus under the wonted figure and action. The adult flustra was 

 vertical^ for the leaf is always erect, but here the new cell is /lori- 

 zonfal. By a singular provision of nature, as only one side of the 

 adult is cellular, the original cell is necessarily a root, sole, or foun- 

 dation, to admit subsequent enlargement, which in such zoophytes 

 is always from a single cell. One end of the cell next rises verti- 

 cally, wherein a second cell with its polypus is soon displayed over- 

 hanging the first, and at right angles to the plane of its position. 



VOL. XVII. NO. XXXIV. OCTOBER 1834. E 6 



