246 THE INHABITANTS OF THE SEA. 
their juices with a bloodthirsty proboscis. Some (Argulus, 
Caligus) wander about freely on the body of their victims as 
grazing animals on their pasture grounds, or even make ex- 
cursions in the water, where they will turn over and over several 
times in succession like mountebanks; others (Lernee ), after 
having, like the barnacles, indulged in a vagabond existence in 
their first youth, remain ever after clinging to the spot on which 
they originally settled, and where their body undergoes such 
remarkable transformations that not a vestige of the crustacean 
structure which characterised their erratic life remains. 
As we continue to proceed from the lower to the higher forms, 
we find, on the next stage of crustacean life, the numerous 
families ofthe Entomostraca ; some bristly-footed (Lophyropoda), 
withasmall number of legs and with respiratory organs attached to 
the parts in the neighbourhood of the mouth, others gill-footed 
(Branchiopoda), with numerous foliaceous legs, serving both for 
respiration and swimming. Some of these creatures, which are 
generally of such minute size as to be only just visible to the 
naked eye, have an unprotected body (Branchipus), but gene- 
rally they are enclosed within a horny or shelly 
casing, which sometimes closely resembles a 
bivalve shell in shape and in the mode of junction 
of its parts, whilst in other instances it forms a 
kind of buckler, an opening being left behind, 
through which the members project. 
Though enjoying a royal title, the King-crabs, 
or Limuli, occupy in reality but a low rank 
among the crustaceans, and are hardly superior in 
King-Crab. organisation to the Entomostraca. They are of 
large size, sometimes attaining the length of 
two feet, and of a very singular structure, the bases of the legs 
performing the part of jaws. The best-known species comes from 
the Moluccas, where they are often seen slowly 
swimming in the sheltered bays, or still more 
slowly crawling along upon the sandy shores. 
In the Edriophthalmia are included the lower 
oian ae crustaceans that have no carapace, and whose 
thorax and abdomen are distinctly composed of articulated 
segments. The numerous legs are variously formed in the diffe- 
rent genera for springing, walking, or swimming; and respira- 
