64 EVENINGS AT THE MICROSCOPE. 



times, the Bird's-head Coralline, the latter name being 

 assigned to it for a reason which you will presently per- 

 ceive. The appellation by which it is known to naturalists 

 is Bugula avicularia. 



We drop our specimen into a very narrow cell, com- 

 posed of parallel walls of thin glass, a very minute flat- 

 tened tank, in fact, such as can be put on the stage of the 

 microscope. Here, bathed in its native sea-water, as 

 clear as crystal, we shall see it opening and expanding its 

 numerous polypides with the utmost activity and evident 

 enjoyment. 



You gaze ; but you know not what you see. The pre- 

 sence of many lines, representing transparent vessels of 

 strange and dissimilar shapes, overlying each other ; and 

 the swaying to and fro of curious objects, which strike 

 now and then forcibly across the field of view, are quite 

 bewildering. I must act the showman, and tell you what 

 to see. 



The cells are oblong, shaped much like a sack of corn, 

 with a spine ascending from each of the upper corners. 

 Each stands on the summit of its predecessor in the same 

 row, and side by side with those of its fellow-rows, in 

 such an order that the top of one cell comes opposite the 

 middle of the one beside it. The top of the sack is 

 rounded, and appears closed, but we shall presently find 

 an opening there. The broad side that faces inwardly has 

 a large elliptical transparent space occupying nearly its 

 whole surface ; this is covered with a very thin and elastic 

 membrane, and answers a peculiar end. Just below one of 

 the spines that crowns the summit of the cell on one of the 

 edges, is situated a little lump, to which is attached, by a 

 very free joint, an object which you will perceive to bear a 

 remarkable resemblance to the head of a bird of prey. It 

 has a beak strongly hooked, with two well-formed man- 

 dibles, of which the lower is movable, shutting into the 

 cavity of the upper ; you observe it deliberately opening, 



