SEA-MATS AND SHELLY CORALLINES 81 



ence of many lines representing transparent vessels of strange" 

 and dissimilar shapes, overlying each other; and the sway- 

 ing to and fro of curious objects, which strike now and 

 then forcibly across the field of view, are quite bewilder- 

 ing. 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 mid- 

 dle 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 el- 

 liptical transparent space occupying nearly its whole sur- 

 face; this is covered with a very thin and elastic mem- 

 brane, 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, 

 like that of a bird, only stretching to an enormous width 

 of gape, and then closing with a strong and sudden snap. 

 Now and then the whole head sways backward and for- 

 ward on its joints; and these movements, combined with 

 the fitful and apparently spiteful snappings, performed by 

 many birds' heads scattered about the branch, are highly 

 curious and amusing. 



The birds' heads, however, are not the living inhabi- 

 tants of the cells ; they are not integral parts of them. The 



