188 LECTUHE XI. 



Among the species of Lepas without the co- 

 riaceous tube or stem, or such as are immediately 

 affixed by the base of the shell, one of the most 

 common is the Lepas Balanus of Linnaeus, or com- 

 mon Acorn-Shell; frequently seen about almost 

 all the European coasts, on rocks, &c. and a 

 smaller species, extremely resembling it, is often 

 seen grouped on the backs of Oyster-shells. The 

 animals of the whale tribe are often infested by 

 various kinds of Lepades, some of which are merely 

 affixed to the surface, while others are deeply im- 

 bedded, to the distance of (some inches beneath the 

 cuticle. 



Having thus given a general description of the 

 testaceous tribe, we have to observe, that the shell- 

 animals are produced from eggs, which in some 

 species are gelatinous, and in others covered with 

 a calcarious shell; and that the young animal 

 emerges from the egg with its shell on its back : the 

 most familiar and convincing proof of this may 

 be obtained by observing the evolution or hatch- 

 ing of the eggs of the common Garden Snail, as 

 well as of several of the water-snails, which depo- 

 sit eggs so transparent that the motions of the 

 young, with the shell on its back, may be very dis- 



