VARIOUS LODGINGS 17 



colouring. Where wooden piles have been driven into the 

 shore within tide-marks, the part which the water reaches 

 IS almost sure to be very soon attacked and taken posses- 

 sion of by two or three very distinct crustaceans, the two 

 constant companions being the strange amphipod Ghelura 

 terebrans, with a name signifying the boring claw-tail, and 

 a perhaps equally mischievous isopod, known as Limnoria 

 lignorum, or the Gribble. With these is frequently asso- 

 ciated one of the cheliferous isopods, the species Tanais 

 vittatus in England, and Tanais filum in America, not con- 

 cerned, it may be, in making the excavations, but only 

 using them when made. Some Amphipoda and Isopoda 

 shelter themselves in sponges and some in the branchial 

 sacs of Ascidians. 



Many free-living Copepoda may be obtained in rock- 

 pools and by washing seaweeds, others from various Asci- 

 dians. Those parasitic Copepoda, which are commonly 

 known as fish-lice, may often be procured by examining 

 fishes when first brought to shore, and before they have 

 been prepared for display on the fishmonger's board. New 

 species of Crustacea have sometimes been discovered by the 

 examination of the contents of a fish's stomach. This 

 same repository will also occasionally yield good specimens 

 of already known species. 



The Cirripedes are all marine, most of them impatient 

 even of brackish water, although one species, Balanus 

 improvlsus, Darwin, will live contentedly for some time in 

 water that is quite fresh. Several species are obtainable 

 between tide-marks. Many attach themselves to the sub- 

 merged sides of ships, and to other floating objects. Some 

 make their home in sponges, corals, or shells, and in con- 

 sequence specimens not sought for their own sake are 

 frequently distributed by the commerce of which their 

 dwelling-places are the more direct object. 



For the Gigantostraca collectors in England must 

 content themselves either with fossil or with imported 

 species. In New England, the horseshoe crab, Limulus 

 polyphemus, may be had at or just below low water. 



By availing himself, then, of those Crustacea which 



