FLUSTRA. 5 



the plain and delicate texture of such a leaf. All the hydra? of zoophytes 

 being revived by the freshness of the surrounding medium, as already seen, 

 so are those of Flustme most induced to protrude on a renovated supply. 

 But here also do some continue so long in pertinacious retreat, either to 

 cast the skin, or for some other purpose, that recent sea-water proves in- 

 sufficient to rouse them from their dwellings ; while on different occasions, 

 what was so stale as ten days old has been effectual. 



The best, the largest — likewise the most numerous specimens falling 

 into my hands, have been obtained by means of those employed in the 

 skate fisheries. The rest were always of inferior dimensions, and com- 

 monly impaired. But, although more abundant in particular places, fine, 

 entire, and ample specimens are rare ; and it was long before I could pro- 

 cure one of the quality of that which is represented in Plate I. 



The structure of this product seems less adapted to resist the turbu- 

 lence of the waves, from the dimensions and fragility of the parts ; but 

 Nature has provided a yellow marginal band, of different texture from the 

 rest of the leaf, apparently to secure the stem, which is the part in greatest 

 peril of rupture. 



Perpetuation. — Prolific specimens occur at most seasons of the year, 

 even in the depth of winter. They are found, likewise when the cells 

 are occupied by vigorous hydrse. Then the leaf is studded with bright 

 orange corpuscula in the empty cells, while others are tenanted by living 

 hydras, fig. 3. We know that in different zoophytes the parent hydra 

 perishes, as the elements of its offspring advance to maturity : I cannot 

 affirm that the same is concomitant on the propagation of the present 

 subject, because it has not been actually witnessed. 



During my earlier observations, a fragment of a shell bearing a speci- 

 men was detached, and for convenience, affixed with sealing-wax to a 

 piece oT polished carnelian as an artificial sole. 



Having transferred it to a capacious vessel of recent sea-water, the ' 

 protrusion of numerous hydrae at night, proved the healthly condition of 

 the whole, which ought to be always the primary care of the naturalist in 

 conducting his experiments. 



On March 14. many yellow, solid, and consistent-looking spherules 



