44 ZOOPHYTES. 



specimen is represented among the figures in the first edition of Dr John- 

 ston's work. 



Examples of the diversity of aspect and dimensions, are given in 

 Plate XVII. figs. 1, 2, 3, 4, 5. It is problematical whether any one of 

 them would be identified with the rest by the lapse of time. 



Of these, the first was very minute, being scarcely an eighth of an 

 inch in height, and resembling a fine, regular-shaped fig or pear. Small as 

 it was, hydrse protruded from the surface. I felt disposed at the time to 

 consider this the young of a species, which had once occurred, of much 

 larger dimensions, alike symmetrical, growing as a perfect pear, nearly 

 four inches high, from a shell of the Venus Islandica. Though exhibiting 

 no hydrse, I long thought this fine subject an Alcyonium, but at length I 

 concluded it to be a sponge. I shall take an opportunity of introducing 

 its figure, along with a few sponges, in another place. The small Alcyo- 

 nium, Plate XVII. fig. 1, which is better exposed as enlarged, fig. 2, 

 proved an interesting object under the microscope. 



Minute specimens, whether of regular or irregular form, are often 

 sheltered in the empty cavity of bivalve shells. They then resemble 

 diminutive fungi ; but from supervening decay, their history could never 

 be followed further. 



If the larger Alcyonia vegetate in a pendent position, from submarine 

 shelving rocks, their form may be affected as compared with those grow- 

 ing vertically. Many are more arborescent, and evidently of greater' 

 strength and consistence, perhaps owing to external causes. 



Though participating so much of vegetable resemblance, they have 

 nothing like a proper root. 



A specimen ten inches and a half in height, was founded on a shell 

 of the Venus Islandica. When detached, the base only about two lines 

 in diameter, separated, with the under surface smooth, free of any kind 

 of radicles securing its place, as seems always the case of the Alcyonium 

 gelatinosum, which has none. Here the colour was of the palest green. 



A numberless host of hydrse covers the entire surface of the Alcyo- 

 nium, from the root to the extremities, rising like a thin cloud interposed 

 between the subject and the eye. 



