252 MARINE INVERTEBRATES 
shed, and in the spring of the year these thin, glossy casts are found 
in abundance floating on the surface of the water near the shore. 
There are but three orders of barnacles, namely, those in which 
the shell is directly attached to the rocks, those which are attached 
to floating objects by a long stalk, and those which are parasitic 
on animals. A species of the third order infests the whale. 
The older zodlogists classed barnacles with the Mollusca, but in 
1829 Vaughan Thompson, in the study of their embryology, 
found that they should be classed with crustaceans, in company 
with crabs, shrimps, and water-fleas, with which their immature 
forms show direct relationship. 
Genus Lepas 
This genus is commonly known as the ship-barnacle, also as 
the goose-barnacle. It attaches itself to floating logs as well as 
to ships, but the latter form its principal home; consequently it 
is a great voyager, and, though common everywhere, is every- 
where considered a stranger. The same species are found on 
ships coming from the most remote and widely separated regions, 
and so they cannot be considered native to any one locality. 
They are wanderers on the deep, and grow in such numbers on 
the bottoms of ships, especially of those which sail in warm seas, 
that they seriously impede the progress of the vessels. Aside 
from diminishing its speed, they do a ship no injury. 
There was a tradition, which lasted several centuries, that geese 
were hatched from these shells, which somewhat resemble eggs. 
Gerard, in the appendix to his “ Herball or Generale Historie of 
Plants” (1597), gives a picture of shells of Lepas growing on a 
tree, with geese falling from them and swimming about in the 
water below. His description is as follows: ‘There are founde 
in the North parts of Scotland and the islands adjacent called 
Orchades certaine trees whereon do growe certaine shell fishes of a 
white color, tending to russet, wherein are conteined little living 
creatures ; which shells in time of maturitie do open, and out of 
them grow those little living foules whom we call barnakles, in the 
North of England brant geise, and in Lancashire tree geise; but 
