PLUMATELLID.E : ALCYONELLA. 399 



two complete colonies, indepeudent of each other, one of which some- 

 times removes itself to another part of the vessel. The manner how 

 the single animals propagate I have not been able to discover, though 

 there is some reason to conjecture it may be by the means of eggs ; 

 as small opake bodies of a constant and determinate figure are some- 

 times seen lying in their bells ; and unless they are eggs, I know not 

 what to make of them. Their shape is nearly that of a weaver's 

 shuttle, being composed of two circular arcs, whose concave parts are 

 towards each other. The breadth is about two-thirds of the length, 

 and in the middle of each a circular spot appears more opake than the 

 rest, which possibly may be the embryo. But, as I never saw any of 

 them come to perfection, I can make no further judgment of them 

 than w^hat their situation and form suggests. 



" The bells or colonies of these animals are to be found adhering 

 to the large leaves of duckweed and other aquatic plants ; and may 

 easiest be discovered by letting a quantity of water with duck-weed 

 in it stand quietly for three or four hours in glass vessels, in some 

 windoAv or other place where a strong light comes ; for then, if any 

 are about the duck-w^eed, they will be found on careful inspection 

 extending themselves out of their cases, spreading their plumes, and 

 making an elegant appearance. 



" They are extremely tender, and require no little care to preserve 

 them : their most general disorder is a kind of slime or mouldiness, 

 which will sometimes envelope them in such a manner as to prove 

 mortal. The best way of curing this is by gently pouring a large 

 quantity of water (perhaps two or three quarts) into the vessel where 

 they are kept, and letting it run off slowly ; by which means the 

 sliminess will gradually be loosened and carried away w4th the 

 water. 



" As to food, if fresh water be given them daily, they will find suf- 

 ficient for themselves ; and it is dangerous to try any other way of 

 feeding them, for the smallest worms or other visible insects one can 

 think of giving them will tear their delicate frame in pieces." 



Pallas has added nothing to the history of this polype, which he 

 had, nevertheless, personally examined. Bosc, having collected, in 

 ponds near Paris, a polypidom of a massive character, apparently 

 unknown, sent it to Bruguiere, who described it as a new species of 

 Alcyonium. The same production having come under Lamarck's 

 inspection, he formed of it the genus Alcyonella, which was imme- 

 diately adopted by all naturalists, for Bruguiere's description of the 



