siinilaiity in ilic form of (lie polyps of any one species, 

 tJie shape of the coh)iiy has vvide limits of possible 

 variation, and consequently a definition of it is almost 

 impossible. 



In other respects, too, the species vary. I'he colour, for 

 example, is sometimes constant, but more generally sub- 

 ject to considerable variation, and the spicules, which are 

 often very characteristic in form, more fre([uently are 

 subject to modification in size and form from that which 

 is regarded as typical of the species. 



The reproduction of the Alcyonarians is remarkably 

 constant. A few species are viviparous, the young being- 

 born as solid, oval, ciliated larvte, which swim away and 

 then settle down to found a new colony. In the majority 

 of cases, however, the eggs and s})erms are discharged 

 into the water sijuuUaneously by tlie male and female 

 colonies, feitilisation is effected in Iju^ water, and soliil 

 oval embryos are produced similar to those of (lie 

 viviparous species. Xo other larval form is known in the 

 group, and nothing occurs in 1 he (kMclopment of any 

 species of the naluie of an alternation of generations. 



With the exception of the Precious Coral, the axis of 

 which is used by jewellers, none of the Alcyonarians have 

 any market value. Xor do the Alcyonarians, so far as 

 we know at present, form an important ar'ticle of food for 

 fish or indeed any other marine animals. It is true that 

 occasionally fragments of Pennatulids are found in the 

 stomachs of Codfish, but thei'e is no reason to believe that 

 they form a frequent nor a favourite diet.* It is possible 

 that at the spawning period of the Alcyonarians many of 

 the eggs and embryos are devoured, but of this there is at 

 present no definite evidence. 



* The Haddock is sometimes found with pieces of tlie Pennatulid 

 Vircjularia in its stomach. Vide A. ]M. & W. P. Marshall, Report on the 

 Oban Pennatulida, Birmingham, 1882. 



