74 Part second. 



of which we will only mention Carcinus (Green Crab, Fig. 137), Eriphia 

 (Fig. 144) and Lupa (Fig. 139). Their agility and slyness are surprising, 

 and, together with their power of living and moving on land, point to 

 a further progress in their organisation. Those who have tried to catch 

 one will remember the difficulty in obtaining even one of a hundred, 

 and will have noticed how cleverly the little fugitive availed itself of 

 every hiding-place, and how boldly it defended itself when finally driven 

 into a corner. The strong Eriphise are especially ready to fight, and 

 with their strong claws they pinch violently every thing which is held 

 out at them. In the Aquarium they have been seen to break thick glass 

 tubes. 



Out of the water all Shore-crabs can live a considerable time and 

 move about with as much agility as in their native element. 



Besides all these Crustaceans with five pairs of legs ( Decapoda) we 

 must refer to a genus belonging to the Stomatopoda. This is the Man- 

 tis-prawn (Squilla mantis, Fig. 148) a slender, agile, and predacious 

 animal which in the shape and position of its claws greatly resembles 

 a well known insect, the Praying Mantis (Mantis religiosa). Its legs 

 have claws that close like the blades of a penknife on its handle; and 

 it can dart them at its victim with great force and velocity, like the 

 predacious insect which it resembles. The Mantis-prawn is a very clean 

 animal, and almost constantly occupied in carefully cleaning all parts of 

 its body. It may be seen in all sorts of attitudes, performing its toilet. 

 Now the eyes and feelers, now the mouth and its appendages, now the 

 legs and joints of the body are brushed and stroked, till no foreign 

 particle is left adhering to them. 



Up to the present we have dealt with Crustaceans of considerable 

 size, which at once strike the eye; but now we must spend a little time 

 over their smaller kin. 



The large group of the Crustacea comprises such a variety of forms, 

 that only those zoologists especially studying this group have a con- 

 ception thereof, and by far the greater number of species are unsuitable 

 for exhibition in an Aquarium. This is due in part to their smallness, 

 often accompanied by entire transparency, so that they cannot be seen 

 with the naked eye; in part to their secluded habits. We must con- 

 fine ourselves to those more striking forms which are occasionally exhi- 

 bited in the Aquarium. 



Almost all the year round most of the tanks, especially Nr. 7 and 

 11, contain swarms of very minute, lively shrimps, which play about 

 over the sand like a swarm of flies. These are not the young of some 

 larger shrimp, but fully grown animals, the Opossum-shrimps or Mysi- 

 dea. They are remarkable for having their organ of hearing quite in 

 their tails, and each leg terminating in two prongs. The higher forms 

 of crabs have such "bifid" feet at the earlier periods of their life and 

 have probably sprung from some form similar to the Mysidea of to-day. 



Out of the group of the Isopoda (of which the wood-louse is a 

 typical example, being an Isopod which has taken to terrestrial life) 

 visitors may often see the parasitic forms Anilocra and Cymothoa 

 (Fish-lice) fixed to various fishes. They are attached to the head, the 



