184 BY THE DEEP SEA. 



balanoides] that crust the rocks between tide-marks. We 

 might have used the expression " too-familiar," for whoever 

 has had to put a bare-foot upon them in bathing or swimming 

 from the rocks, will have had cause for remembering their 

 sharp edges. It is not easy to keep the Ship-barnacle in an 

 aquarium ; but a flake of rock, or a disused limpet shell, 

 crusted with Balanus, is conveniently kept in a glass of sea- 

 water, and will long continue at once a thing of beauty and a 

 wonder to friends who are ignorant of natural history. These 

 are sessile Cirripedes, that is, they have no stalks upon which 

 to writhe, but sit directly upon the rock. 



If we scrape one of these Acorn-shells off the rock with our 

 useful putty-knife, we shall find that it has a thin base of shelly 

 matter upon which it reposes much as the Ship-barnacle does 

 upon the floor of its shelly chamber. But it will be seen that 

 the sloping outer walls of the Acorn-shell are firmly cemented 

 together, and allow of no movement ; the top, however, is 

 open, but the animal within is protected by an interior door 

 of four pieces, that opens in the middle like the cellar-flaps 

 seen in connection with business basements. These doors 

 u butt" together accurately, and open easily by pressure from 

 inside. Then out comes a more beautiful and delicate " hand" 

 even than that of the Barnacle, for this is so fine and trans- 

 parent that it looks a thing of spun glass. There is the same 

 movement as in the Barnacle, the everlasting grasping at 

 something, the opening and shutting of the cellar flaps. Its 

 earlier history is also similar to that of its stalked relation. 

 There is a larger species of Acorn-shell known as the Porcate- 

 barnacle (Balanus porcatus), the name having relation to the 

 form of the conical shell ; porcate signifying that it has ridges 

 between the furrows that mark its outside. Other species, 

 smaller, some almost flat, will be found on some parts of our 

 coast, but we would refer our readers to Mr. Darwin's work* 

 for the further study of the Cirripedes. 



* A Monograph of the Cirripedia, 2 vols. Ray Society* 



