ENEMIES OF THE CRUSTACEANS. 259 



PhyllosomaSf thin as a leaf of paper, and so transparent that 

 their blue eyes are their only visible parts while swimming in 

 the water ; and yet these flimsy creatures are nothing but the 

 young of the large and bulky Palinuri. 



Though several of the lower crustaceans ascend into the 

 regions of eternal snow, while others hide themselves in the 

 perpetual night of subterranean grottoes ; though many delight 

 in the sweet waters of the river or the lake, or rapidly multiply 

 in stagnant pools, yet the chief seat of their class, which alto- 

 gether comprises about 1,600 known species, is in the ocean 

 and its littoral zone, where their numbers, their voracity, 

 and their powerful claws, render them the most formidable 

 enemies of all the lower aquatic animals that are not 

 swift or cunning enough to escape them. Even the fishes 

 and cetaceans are, as we have seen, exposed to their attacks ; 

 and as the whale, the carp, the sturgeon, the shark, the perch, 

 have each of them their peculiar crustacean parasites, it can 

 easily be imagined how large the number of still unknown 

 species must be which feast on that vast host of fishes that has 

 never yet been accurately examined. On the other hand, the 

 crustaceans constitute a great part of the food, as well of the sea- 

 stars, sea-urchins, annelides, and many of the molluscs, as also 

 of the fishes and sea-birds ; and as they are found of all sizes, 

 from microscopical minuteness to the gigantic proportions of 

 the Inachus Kcempferi of Japan, the fore-arm of which measures 

 four feet in length, and the others in proportion, so that it 

 covers about 25 feet square of ground, they are able to 

 satisfy the wants or the voracity of a vast number of enemies, 

 from the rotifer or the polyp that feed on tiny entomostraca or 

 the larvae of the barnacle, to man, who selects a great variety 

 of the fat and luscious decapods for his share of the feast. 



A great fecundity enables the crustaceans to bear up against 

 all these persecutions. 12,000 eggs have been found on the 

 lobster; 6,807 on the shrimp; 21,699 on the great crab 

 (Platycarcinus pagurus). The lower orders are still more 

 prolific, for such is the rapidity with which many of them come 

 to maturity and begin to propagate that it has been calculated 

 that a single female Cyclops may be the progenitor in one year 

 of 4,442,189,120 young! Endowed with such powers, the 



