72 Part second. 



all is right, it cautiously prepares to effect the removal. It gets hold of 

 the shell with its claws, places it in an upright position with the opening 

 toward itself, and with one quick dart forsakes its old shell and slips 

 into the new one, as if it well knew what a tit-bit its soft juicy body 

 would be for a hungry fish. 



But why should often three or even six Sea-anemones be so regularly 

 attached to the shell occupied by the Hermit-crab , ad yet be in no 

 way organically connected with the crab ? It is evidently a friendly 

 alliance which has sprung from some mutual advantage gained ; this 

 consists, so far as we can see , in the Hermit-crab being protected by 

 the poisonous stinging-cells of the Anemone (see p. 56), so that its ene- 

 mies (turtles and cuttle-fish) are kept at bay by the pain they experience. 

 The Anemones, on the other hand, have a greater chance of finding food; 

 as they need not wait , like those fixed to a rock , till the food comes 

 within their reach, but are constantly brought into contact witg all kinds 

 of animals by the vagabond life of the crab, and may occasionally catch 

 some bits of the crab's own meal. This is the case with the beautiful 

 purple-spotted Anemone Adamsia palliata (Fig. 165), which is always 

 fixed to shells inhabited by the EupagUFUS Prideauxii , and is so 

 placed that it can catch what falls from the lips of the crab. But the 

 most wonderful thing is that the crab knows its friend , and not only 

 tries to put anemones on shells which are devoid of them , but actually 

 takes its companions along with it, when it changes its house! Observations 

 and experiments have placed this beyond all doubt , and prove this al- 

 liance to be one of the most remarkable known among lower animals. 



The life of the Hermit-crabs in the Aquarium is rich in varied and 

 amusing scenes. The droll fights of the little troop, the way they tumble 

 about, flee and follow each other up , the impudent seizures of some 

 and resolute defence of the others during the common meal invariably 

 excite the laughter of the spectator , who is often greatly surprised at 

 the artful and calculating ways of the little creatures. In these habits 

 the Hermit-crabs rank next to the true Crabs , to which we will now 

 turn our attention. 



In the Hermit-crabs we noticed a retrogression in the rudimentary 

 development of the tail , brought about by their mode of life. In the 

 short-tailed Crabs (Brachyura) this retrogression has gone still further, 

 but has been accompanied by an increase in agility. Here the large 

 portion of the body which forms the tail of the lobster , is reduced to 

 a small round or triangular plate which is doubled up under the stomach- 

 region and is therefore not seen from above. The anterior part of the 

 body is laterally expanded and is mostly of a roughly triangular or 

 square shape; the well known Shore-crab may serve as a type. 



To begin with, we would mention the Crabs with a triangular 

 body. The first point which will attract notice in these , is the curious 

 way in which they are covered with all sorts of foreign substance; thus 

 Pisa (Fig. 146) carries quite a forest of small algae and colonies of animals 

 (Polyzoa and Hydroid-polypes) on its back and legs: Inachus (Fig. 145) 

 carries about on its slender legs plants, sponges, and ascidians; in fact, 

 the more crabs we examine the greather is the variety of toilets that we 



