1877.] Barnacles. 103 
So rotten planks of broken ships do change 
To Barnacles. O transformation strange ! 
*T was first a green tree, then a broken hull 
Lately a mushroom, now a flying gull.” 
The transformations described by the above authors are, it is 
needless to say, founded wholly upon fancy, but the metamor- 
phoses observed in a study of the life-history of a barnacle are 
scarcely less wonderful than those so minutely related by the 
old botanist. The old idea is still perpetuated in the names of 
two animals: that of the “ Barnacle Goose” (Bernicla), and in 
the specific name of one species of barnacle, the Lepas anseri- 
fera of Linnzeus. 
Barnacles were at first classed among the Mollusca, on ac- 
count of their calcareous valves, as were at a later date the 
Brachiopoda ; but in 1828-29 John Thompson proved, by studies 
of their embryology, that they had absolutely no molluscan affin- 
ities, but that they were Crustacea. Later investigations of 
their anatomy have confirmed this and they are now aecorded a 
place among the lowest Crustacea, the Rhizocephala only being 
below them. 
They form the sub-class Cirripedia, and are divided into two 
orders : the first is the pedunculated Cirripedia, in which there is 
a capitulum, generally formed of caleareous valves, varying in 
number, and united by membranes, and a tough leathery stalk, 
the peduncle, by which they are attached ; in the other order, the 
sessile Cirripedia, the capitulum has four or more of its valves 
immovably united, and is directly attached without the inter- 
vention of a peduncle. 
In Figure 5 we give the anatomy of one of the peduncu- 
lated forms, Lepas fascicularis of Ellis and Solander. In this 
Species the capitulum is composed of five valves, two on each side, 
and one on the dorsal edge. The ventral margin is open and 
the two basal valves are connected by an adductor muscle (A, e), 
by which this opening can be closed. To dissect a specimen, it 
should be placed under water in a wax-bottomed pan and pinned 
down. In this manner the parts float out and the various organs 
are easily seen. The valves of one side are removed by cutting 
the adductor scutorum muscle and the membranes uniting them. 
This discloses a body with six pairs of long ciliated arms, the 
cirri (A, c), which represent the thoracic feet. Each cirrus con- 
sists of a basäf portion and two long jointed branches. They de- 
crease in length as we go forward (that is, toward the peduncle). 
In front of these cirri we find a protruding organ formed by the 
