iyo THE BRITISH NATURE BOOK 



crabs, has four horns on its very long beak, and many short spikes and hairs 

 on its back. It is frequently covered with seaweeds or corallines. 



The Pea Crab (Pinnotheus pisum] when full grown is about half an inch across, 

 and very round ; yellow in colour. It lives inside the shells of living mussels 

 and other bivalves a very remarkable instance of " partnership " in animals. 



The Hairy Crab (Pilumnus hirtellus) is a small species covered with hairs 

 and spines, with large claws ; common on the South and West Coasts. 



The Angular Crab (Gonoplax rhombides) is identified by the many sharp 

 angles of its back, which is reddish brown in colour, and its long pincer claws. 

 It has specially long eye-stalks, and lives in mud. 



"Zebedee" (Xantho hydrophilus) is one of a genus of yellowish-coloured 

 crabs known as Devil-crabs, or Zebedees, having the shell much wrinkled and 

 with the fingers of the pincer-claws brown (in X. incisus, black). 



The Broad-claw (Porcellana platychdes) is a very flat and dirty species 

 inhabiting mud, found in tidal estuaries. It is quite small, hairy on the back, 

 but a smooth, creamy white below : hence the name " HAIRY PORCELAIN 

 CRAB." 



Hermit Crabs. There are many species known by this name from the 

 fact that, having soft tails, they protect them by living in the abandoned shells 

 of molluscs, which they thus carry about with them, like snails ! They are 

 very pugnacious, and often fight one another for a coveted shell. The common- 

 est is Eupagurus bernhardus when full grown 5 inches long, inhabiting large 

 whelk shells. One of the most interesting is Eupagurus prideaux, which plants 

 an anemone (the Cloaklet, Adamsia palliata) on its shell. This " friendship " 

 serves both parties well, for as no fish will devour an anemone, the crab is thus 

 protected from enemies, whilst the anemone profits by being carried to any 

 meal which the crab obtains. 



These crabs make interesting inhabitants of the aquarium. 



The Wood-louse belongs to a family included in the order known as Isopoda 

 (" Equal-footed "), and it is well to be reminded that the curious little creature 

 found in our gardens, under stones and decaying wood, is not an insect, but a 

 crustacean. Its strong armour o'f grey plates, its long antennae, and its seven pairs 

 of walking legs, are its most familiar characteristics ; but it is worth a closer 

 inspection. Then it will be seen that the abdomen has six pairs, the first five 

 overlapping like tiles, the sixth modified to hold air. The process of reproduc- 

 tion is most remarkable, but it must suffice here to refer to the fact that the 

 eggs are carried in certain brood chambers on the legs until they are hatched. 

 Wood-lice feed on vegetable matter, both fresh and decayed. At least one 

 species (Armadillidium vulgar e) is able to roll itself into a ball when alarmed. 

 In old days this habit was considered to show its value as a medicine, and it 

 was actually used as a pill ! 



A large marine species is often found under stones on a rocky shore the 

 Sea-slater (Ligia oceanica). 



