3248 



THE JOINTED ANIMALS 



ACORN BARNACLE. 



(Natural size.) 



to the bottoms of ships or floating timber, and the acorn barnacles covering the 

 rocks on the coast. The barnacle (Lepas) consists of a tough longer or shorter 



stalk, one end of 



which 



adheres 



H tightl} r by means 

 of a cement to the 



==a 



| timber or ship, 

 H while to the other 



is attached an 



oval compressed 

 | body incased in 

 j. pieces of shell, 



f through two of the valves of which can 

 | be protruded six pairs of slender, bristly, 

 | two-branched, filamentous limbs. These 

 | limbs, being the appendages of the thorax, 

 | keep up a constant sweeping motion, 

 H whereby particles of food are washed into 



the mouth that lies 



below them. The 



abdomen is undevel- 

 oped; but the rest of 



the body is enveloped PARASITIC CIRRIPEDE, 



in a fold, or mantle, 



supporting the outer 



shelly skeleton. The jaws consist of two 



STALKLESS BARNACLE. 

 (Natural size.) 



Sacculina. 

 (Natural size.) 



pairs of maxillae, and a pair of mandibles, and the 

 lower part of the head is inferiorly continued into the 

 stalk, which contains the gland secreting the cement. 

 If a barnacle be carefully removed from its point of 

 attachment, the remains of the first pair of antennae 

 may be observed on the adhesive surface. When first 

 hatched, the young are in the Nauplius stage, being 

 furnished with a median eye, and three pairs of ap- 

 pendages, of which the posterior two are branched. 

 After swimming for a while by means of these ap- 

 pendages, the larva molts several times, and passes 

 into a second stage, in which, with its two eyes and 

 compressed carapace, it resembles a Dapknia, The 

 rudiments of the six pairs of thoracic legs appear be- 

 hind the mouth, and the first pair of swimming ap- 

 pendages, become antenniform, each being provided PARASITIC BARNACLES. 

 with a sucker. By means of these suckers the larva upper Figure - Peitogaster curvatus 

 fixes itself to its permanent resting place, and, the (enlarged i times); i,ower 



Figure Nauplius larva of Par- 



cement gland pouring out its secretion, glues the crea- thenopea (enlarged 200 times.) 



