PYCNOGONIDS— SEA-SPIDERS— KING-CRABS 37 1 



If kept in cold water, the members of the genus Nymphon flourish in 

 aquariums. All of them crawl, but a few are also able to swim by the aid of 

 swimming-hairs, which are more strongly developed in males than in females. 

 They feed entirely on the polyps of Hydrozoa, more especially those of the family 

 Campanulariidce, the mode in which these organisms are seized and devoured 

 being very curious. The species of Pycnogonum, which, as already mentioned, 

 are parasitic on sea-anemones, the juices of which they suck, are much more 

 difficult to keep in confinement. 



The beach, let alone the sea itself, might at first sight be 



regarded as a highly unpromising situation for spiders, yet as a 



matter of fact representatives of the Arachnida are to be found both on the shore 



and the open sea. On the rocks and coral-reefs of the Indo-Pacific there are to be 



found, for example, representatives of a group of web-spinning spiders constituting 



AMERICAN KING-CBAB. 



the family Desiche. When the tide comes in, these sea-spiders retreat to holes where 

 they remain in safety till the next ebb, protected by waterproof -sheets of their 

 own manufacture. With the ebb they once more commence to hunt along the 

 shore or to swim in the tide in search of the minute crustaceans and fishes upon 

 which they feed. There are also numerous kinds of truly marine spiders, some of 

 which live at considerable depths, and attain to very large dimensions, measuring 

 in certain instances as much as a couple of feet across the body and legs. 



The so-called king-crab of the Moluccas is a misnamed creature ; 



Kintr-CrEitos 



for, in spite of its somewhat crab-like shell, it is not a crab at all, but 

 rather a near relative of the scorpions, which are first cousins of the spiders, 

 and are consequently included in the class Arachnida — a group of equal rank 

 with the Crustacea or crabs, lobsters, etc. 



King-crabs are protected by a capacious buckler-shaped shell, beneath which 

 the six pairs of limbs are completely concealed ; posteriorly the body ends in a long 

 spear-like spine, by means of which the animal is enabled to elevate the hind part 



