ANATOMY OF THE BARNACLE. 273 
(Fig. 222), a shell-like animal, the shell composed of several 
pieces, with a multivalve, conical movable lid, having an 
opening through which several pairs of long, many-joint- 
ed, hairy appendages are thrust, 
thus creating a current which sets 
in towards the mouth. The com- 
mon barnacle (Balanus balanoi- 
des Stimpson) abounds on every 
rocky shore from extreme high- 
water mark to deep water, and 
the student can, by putting a 
group of them in sea-water, ob- 
serve the opening and shutting 
of the valves and the movements _ Fig. 998.—A barnacle. Balanus 
of the appendages or “cirri.” "7% Natural size 
The structure of the barnacle may best be observed in 
dissecting a goose barnacle (Lepas fascicularis Ellis and 
Solander, Fig. 223). This barnacle consists of a body (capit- 
wlum) and leathery peduncle. There are six pairs of jointed 
feet, representing the feet of the Cyclops (Fig. 231). The 
mouth, with the upper lip mandibles (B, 1), and two pairs 
of maxille, will be found in the middle of the shell. A 
short csophagus (according to J. S. Kingsley, whose ac- 
count we are using) leads to a pouch-like stomach and tubular 
intestine. This form, like most barnacles, is hermaphroditic, 
the ovary (A, 0)lying at the bottom of the shell, or in the 
pedunculated forms in the base of the peduncle, while the 
male gland (¢) is either close to or some distance from the 
ovary. There is also at the base of the shell, or in the pe- 
duncle when developed, a cement-gland, the secretion of 
which is for the purpose of attaching the barnacle to some 
rock or weed. 
While the sexes are generally united in the same indi- 
vidual, in the genera Jbla (Fig. 224) and Scalpellum (Figs. 
225, 226, besides the normal hermaphroditic form, there 
are females, and also males called ‘‘complementary males,” 
which are attached parasitically both to the females and 
the hermaphroditic forms, living just within the valves or 
fastened to the membranes of the body. These comple- 
