HALF AN HOUR WITH CRUSTACEA. 231 



piece of the shell is chambered at the base, and 

 the whole of them form a conical structure, the top 

 of which is closed by two other pieces of shell 

 which meet in the middle, and open and shut 

 like the folding doors of a street cellar. These 

 are thrown open, exactly as cellar doors are by a 

 person beneath, and out pops a feathery hand that 

 snaps at prey and secures it, as in the stalked 

 barnacles. 



And now we beg the reader's attention to the 

 metamorphoses of these curious animals, when it 

 will be seen that, little as they resemble Crustacea 

 when full-grown, they show certain affinities to 

 them when juvenile. The first stage in their life- 

 history is that the young assumes the form and 

 appearance of an Entomostracan, or " Water-flea," 

 having a single eye, two pairs of antennae, and a 

 forked tail. It subsequently moults several times, 

 assuming a different appearance each time. At the 

 third time it resembles a Cypris, and is enclosed 

 within two valves, and has two eyes instead of 

 one. Its great search now seems to be for rocks, 

 timber, &c., and having met with any of these, it 

 exudes a sort of glue and attaches itself. Another 

 moult takes place, the valves are thrown off, and the 

 adult form is assumed. The creature is, in fact, 

 attached by its antennae, and has what in other 

 Crustacea would be legs the same organs modified 

 into the feathery hand of which we have spoken. 

 The fingers of this hand are called " cirri," and, as 



