2l6 



CIRRIPED1A. 



PART III. 



of atoms from the mouth of its shell for several suc- 

 cessive days ; each column was composed of thousands 

 of active microscopic creatures, bearing a strong simi- 

 larity to the young of the Cyclops Crustacea. A, fig. 156, 

 represents one of these creatures. Its body is enclosed 

 in a carapace with a pair of flexible organs like horns, 

 six swimming feet, and a very black eye deeply set 

 in front. The creature swims and sometimes rests, but 

 never alights on anything. After some changes this 



Fig. 156. Development of Balanus balanoides : A, earliest form ; B, larva after second 

 moult ; c, side view of the same ; D, stage preceding the loss of activity ; a, stomach ; 

 6, nucleus of future attachment. 



creature takes a form whose front is represented at B, 

 and its side by c, fig. 156. It is larger, more deve- 

 loped, and swims with its back downwards. 



A new series of transformations changes this embryo 

 into the form represented by D, fig. 156, which is closely 

 allied to the Daphnia pulex, or Water Flea. The body is 

 enclosed between two flat oval shells, united by a hinge 

 on the back, and is capable of being opened in front for 



