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 Balanus balanoides, an 
exceedingly variable form, which makes dense 
crusts on rock-masses, piles, etc. In the typical 
variety the acorns or cups 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 is Balanus ebur- 
BALANUS BALANOIDES. BALANUS EBURNEUS. 
neus, 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. 
