256 CRUSTACEA, ECHINODERMS, ETC. 



tropical shells for the hermit crabs to take up their 

 abodes in, although this has added to the attractive 

 appearance of the bottoms of the tanks. Before moult- 

 ing these crabs generally leave their old domiciles, 

 and select one so much bigger that they can move 

 about in it. Their increase in bulk is then usually 

 very rapid. Many a contest comes off between hermit 

 crabs, when two of them wish for the same empty 

 shell. Every atom of food rejected by other animals 

 in the tank, and which would otherwise lie on the 

 floor and foul the water, is greedily cleared away by 

 hermit crabs and their allies. 



The graceful appearance of lobsters when at rest 

 makes them prominent objects. They seem to be in 

 almost a devotional attitude, resting on their huge 

 pincers as the " praying mantis " does on its fore-legs ; 

 and in this position are often seen with their faces 

 towards the glass front. Their long, slender, jointed 

 antennae are thrown backwards, and are in a constant 

 state of motion. The spiny lobster, or " sea-cray- 

 fish " (Palinnrus quadricornis), is a more attractive 

 marine object than the common lobster, although its 

 flesh is not such delicate food as that of the latter. Its 

 body is covered all over with spines and prickles, and 

 is moreover very brightly coloured. In length this 

 species exceeds any other British Crustacea. It is 

 noticeable, however, by the absence of the large and 

 powerful pincers which distinguish the common lob- 

 ster. The females of this species have spawned both 



