SEA-MATS AND SHELLY COKALLINES. G9 



shell at the bottom of the sea, von Avonld liave seen 

 much more. And what wonhl then have appeared, I 

 will describe to j'on. 



Suppose, then, that a coverlid of transparent shin 

 were stretched over each cradle, from a little within 

 the margin all round, leaving a transverse opening just 

 in the right place, viz. ov^er the pillow, and you wouhl 

 nave exactly what exists here. There is a crescent- 

 form slit in the membrane of the npper part of the cell, 

 from which the semicircular edge, or h'p, can recede, 

 if pushed from within. 



Suppose, yet again, that in every cradle there lies a 

 baby, with its little knees bent up to its chin, in that 

 zig-zag fashion that children, little and big, often like 

 to lie in. But stay, here is a child moving! Softly! 

 He slowly pushes open the semicircular slit in the cov- 

 erlid, and we see him gradually protruding his head 

 and shoulders in an erect position, straightening his 

 knees at the same time. lie is raised half out of bed, 

 when lo ! his head falls open, and becomes a bell of 

 tentacles ! The baby is the tenant-polype I 



"This is a vciy^ amusing romance," you say. Nay, 

 it is no romance at all. If you will excuse the homeli- 

 ness of the comparisons, I will venture to affirm that a 

 personal examination of the creature itself would justity 

 their correctness, and you would acknowledge that they 

 could scarcely be more apt. 



Moreover, the globular chambers show signs of life ; 

 their front doors suddenly open, gape widel}', and then 

 shut with a snap ; and presently this opening and shut- 

 ting is repeated. The meaning of this action you will 

 better understand when we see analogous organs in an- 

 other form of the same class of animals. Meanwhile, I 



