Marvels of the Universe 



553 



only a rudimentary- mouth, which is useless for the 

 absorption of food ; and we must, therefore, conclude 

 that this sajing of the great scientist should, as with 

 all popular sapngs, not be taken too literally, although 

 it forms a good working idea for general use. 



First of all, then, the Barnacle is cousin to the 

 crab. In its early form it is very like the first stages 

 of the crab, and even when it grows older and takes 

 on its peculiar characteristics, it has many points in 

 common with the members of its family. On page 552 

 is shown the young Barnacle, totally unhke its ultimate 

 appearance. It is provided with three pairs of legs (of 

 which each of the hindmost pair develops into two 

 branches), two frontal horns, a single eye on the under 

 surface of the head and a long upper hp. It is caUed a 

 Xauphus. These characteristics are common to every 

 species, but some possess besides long and horny spines, 

 as in the Nauphus shown at the bottom of page 552. 

 What the exact purpose of these spines may be is not 

 yet determined, but it is possible that they assist the 

 tiny creature to float on the surface of the water where 

 it can obtain the minute ocean hfe that serves it for 

 food. After several " moults," the Nauphus is ready 

 to take on the second stage of its existence. It casts its 

 coat once more and is this time completely transformed. 

 It is encased in a two-parted glassy shell, shaped rather 

 Uke a mussel ; another pair have been added to its legs ; 

 instead of one eye, it has two, which have grown one on 

 each side of the original member. A pair of its antennae 

 have gone and the remaining pair have developed into 

 httle tubes, each headed by a disc which acts as a 

 sucker, and into each of these tubes opens a gland. 

 This new individual has, besides, no mouth ; aU that it 

 may require in the way of nutriment is stored up inside 

 the shell, and there is further stored a cement, which 

 wiU be used for the final development of the Barnacle. 

 At this period the tiny creature — which is little more 

 than a quarter of an inch in length — bears a strong 

 resemblance to the water-flea, and is therefore named 

 a Cypris, after one of the members of that group. A 

 further succession of " moults " takes place, during 

 which the posterior feet have increased in size, and in 

 a httle time the Cypris is ready to take on the nature 

 and habit of a mature Barnacle. In its first existence 

 it was forced to seek its awn food and to paddle its 

 own canoe. In the second it stiU paddled, but the 

 canoe held aU the provender necessary for its existence. 

 Now it is determined either to settle down for the 

 remainder of its hfe or to be carried by other means 



/Vi.i/o bu] 



THE SHIP 



With tentacle: 



IHiigh Main, B.Sc, F.E.S. 

 BARNACLE. 



Kalf-expanded. 



Pholri Ijll] UI'I'J'I Main, II. 



THE SHIP BARNACLE. 



With one side stripped ofF to show the 

 the creature in the shell. 



He, F.E.S. 

 position of 



39 



