class="smcap">The Murray River "Lobster," Astacopsis spinifer. New South Wales. Much reduced
The Land Crayfish, Engæus cunicularis. Tasmania. Natural Size

} 177 XXI.   Palæmon jamaicensis. A Large Freshwater Prawn of the Family Palæmonidæ. West Indies. Much reduced   179 XXII.   Atya scabra. A Freshwater Prawn of the Family Atyidæ, West Indies. Reduced   180 XXIII. { The River Crab of Southern Europe, Potamon edule (or Telphusa fluviatilis). Reduced
Sesarma chiragra. A Freshwater Crab of the Family Grapsidæ. From Brazil. Slightly reduced } 182 XXIV.   Æglea lævis. South America. Natural Size   184 XXV.   The Blind Crayfish of the Mammoth Cave of Kentucky, Cambarus pellucidus. Natural Size   186 XXVI. { A West Indian Land Crab, Gecarcinus ruricola Reduced
A Land Hermit Crab, Cœnobita rugosa. Reduced } 190 XXVII.   The Coconut Crab, Birgus latro. Much reduced   196 XXVIII.   Group of Barnacles, Coronula diadema, on the Skin of a Whale. Japan. Reduced   209 XXIX. { Cymothoa œstrum. An Isopod Parasite of Fish. Slightly Enlarged
Sacculina carcini attached under the Abdomen of a Common Shore Crab. Reduced } 220 XXX.   The "Norway Lobster," Nephrops norvegicus. About One-third Natural Size. (From Brit. Mus. Guide)   240 XXXI.   The Common Edible Crab, Cancer pagurus. British. Much reduced   248 XXXII.   Piece of Timber From Ryde Pier, showing Damage caused by Limnoria AND Chelura. (From Brit. Mus. Guide)   255

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THE LIFE OF CRUSTACEA

 

CHAPTER I

INTRODUCTORY

Everyone has some acquaintance with the animals that are grouped by naturalists under the name Crustacea. The edible Crabs, Lobsters, Prawns, and Shrimps, are at least superficially familiar, either as brought to the table or as displayed in the fishmonger's, and the most unobservant of seaside visitors must have had his attention attracted by living specimens of some of the more obtrusive species, such as the common Shore Crab. Many, however, will be surprised to learn that the Barnacles coating the rocks on the seashore, the Sand-hoppers of the beach, and the Woodlice of our gardens, are members of the same class. Still less is it suspected, by those who have not given special attention to the subject, that the living species of the group number many thousands, presenting strange diversities of structure and habits, and playing important parts in the general economy of Nature.

In addition to those just mentioned, a few Crustacea are sufficiently well known to be distinguished by popular names, such, for example, as Crayfish and Hermit Crabs, but for the vast majority no names are available except those of technical zoology. In the following pages, therefore, while technical terms have been introduced as sparingly as possible, the unfamiliarity of the animals themselves makes it needful to use many unfamiliar names.

In the classification of the Animal Kingdom, the Crustacea form one of the divisions of a comprehensive group, or Phylum, known as Arthropoda. The typical members of this group have a more or less firm external skeleton, the body is divided into segments, there are jointed