ORDER II MOLLUSCJE* 31? 



To begin with the medusa. The body of this animal is 

 of an orbiculated convex figure, of a gelatinous substance, 

 and destitute of hair ; and the mouth is below and central* 

 The medusae are sometimes seen swimming in clusters on 

 the surface of the sea, and are said to constitute the prin- 

 cipal nourishment of the whale. Of the various species of 

 this genus, the most remarkable is that which was first no- 

 ticed by Sir Joseph Banks, in his passage from Madeira to 

 Brazil : when drawn up by means of the casting-net, it had 

 the appearance of metal violently heated, and emitted a 

 white light. With these animals were taken three small crabs 

 of different species, entirely new ; each of which yielded 

 as much light as the glow-worm, though the creature was 

 not above one-tenth of the size. These luminous animals 

 give that appearance to the sea which has been observed 

 by many navigators, and for which different reasons have 

 been assigned by different writers. The flashes of light 

 from them exactly resemble those of lightning ; and are 

 so frequent, that several are visible in the same instant. 



The echinus, or sea-urchin, has its body covered with a 

 sutured crust, often furnished with moveable spines which 

 assist its motion ; and its mouth, which is placed beneath, 

 has five valves. The covering, which resembles a scooped 

 apple, is filled with a soft muscular substance, through 

 which the intestines wind from bottom to top. Some spe- 

 cies of the echinus are reckoned equal to lobsters, in point 

 of delicate and wholesome eating, and their eggs, which 

 are of a deep red colour, are highly valued by epicures. 

 The shell, or rather crust, is frequently preserved as an 

 object of curiosity. These animals are generally found in 

 a fossil state. 



The asterias, or sea-star, forms a numerous tribe of ma- 

 rine creatures that are found to vary in their appearance 

 at different periods : the same animal which at one time 

 appears round like a ball, very often, in a short time, be- 

 comes as flat and thin as a plate. The body of the aste- 

 rias is composed of a semi-transparent gelatinous substance, 

 covered with a thin membrane. To an inattentive ob- 



