OUR CARCINOLOGICAL FRIENDS. 107 



line, made up of six plates in its circumference, and 

 with a lid of four plates covering over the central 

 orifice. The feathery appendages of the animal 

 are thrust out from the top of the shell, instead of 

 from the side, as we found it in the goose barnacle. 

 Our commonest species is Balimm bahmoides, an 

 exceedingly variable form, which makes dense 

 crusts on rock-masses, piles, etc. In the typical 

 variety the acorns or cupa are comparatively low 

 and broad, but in the more aberrant forms they are 

 greatly elongated and more nearly tubular in ap- 

 pearance. A much larger species b Bahmus ebur- 





Balajtjs balasohxes. Balajjc? ebueseus. 



TiMts, the * ivory barnacle,' which can be readily dis- 

 tinguished from the preceding by its smooth broad 

 form and its shelly base. It is abundant on all 

 kinds of floating or submerged timbers, and not 

 rarely accompanies the shells of various Crustacea. 

 Much less frequently seen about our coast is the 

 coronated acorn {Coronula diadema), whose seat of 

 habitation is the skin of the whale, with which 

 animal it performs long journeys over the sea. 



