ANTENNULARIA ANTENNINA. 281 



of a bright yellowish horn-colour when fresh. The 

 branchlets are supported on short processes from the main 

 stem, which are ranged in verticils, and are permanent. 

 The pinnules themselves are commonly broken off; and 

 specimens in this condition have much the appearance of 

 the lobster's antenna, whence the name is derived. 



Allman has described a curious peculiarity in the struc- 

 ture of the ccenosarc, which is readily observed in speci- 

 mens preserved in fluid. " Instead of forming a single 

 tube, it consists of numerous separate tubules, each with 

 its ectoderm and endoderm. The tubules lie close upon 

 the polypary, and leave an unoccupied space in the axis 

 of the stem/' This peculiar structure gives a lined ap- 

 pearance to the stems. 



The female capsule contains one sporosac (occasionally 

 two) , in which a single yellow ovum is produced ; and this 

 gives rise to a planuloid embryo of large size*. 



In its earliest state the branchlets of A. antennina are 

 arranged alternately, and there is no tendency to the ver- 

 ticillate condition characteristic of the adult; in a more 

 advanced stage they form alternate pairs. 



This species is sometimes slightly branched, but the 

 branching is of the simplest kind, amounting to nothing 

 more than an occasional bifurcation of the long slender 

 shoots. 



Hob. Generally distributed in deeper water, and com- 

 monly on a sandy bottom. 



[Belgium, common (Van Ben.): La Chareute inferieure, 

 pretty common (Beltremieux).] 



* Sir J. Dalyell says that it is nearly one-twelfth of an inch in length. 



