126 SIDNEY P. HARMBR. 



one described by Smitt/ in which a "basis rami" had given 

 rise to a normal branch, and also to a growing-point directed 

 straight downwards from its base, which was formed by the 

 proximal end of the " basis rami," from which it was separated 

 by a joint. 



Although regenerated lateral branches may start from the 

 old lateral joints, it is not uncommon to find that they are 

 given off from near the end of the old internode, instead of in 

 their normal position lower down ; this is due to the fact that 

 the aperture of an old zooecium has become a growing-point. 



In colonies in which the process of regeneration is com- 

 mencing, it is frequently noticed that the young growing- 

 points are appreciably smaller than the normal ones. These 

 small growing-points naturally give rise to slender zooecia and 

 branches, which, however, as they grow longer, acquire fresh 

 strength, and soon regain their normal diameter. The regene- 

 rated parts of a colony are, consequently, often joined to the 

 older parts by slender bases, in which, moreover, the basal 

 internodes may consist of an unusually small number of zooecia. 

 In both these respects they resemble colonies which are deve- 

 loped directly from the larva, or from a growing-point which 

 starts from the rootlet of an old colony. 



It is important to notice that, so far as my observations go, 

 the regenerated parts of a colony always retain the same specific 

 characters as the older parts. I have looked in vain for any 

 indications which might have been given by regenerating 

 colonies tliat the forms of Crisia described above as distinct 

 species might be merely different phases of the same species. 



The general life-cycle of C. eburnea may probably be sum- 

 marised as follows : — The breeding season is at its height in 

 April and May ; and at about this period it is not difficult to 

 find young individuals which consist of a single zooecium 

 attached by a disc-like base, and which have resulted from the 

 metamorphosis of a free larva; small colonies are soon formed 

 by these primary zooecia. At first, rootlets may be altogether 

 absent, and in many colonies they are developed very sparingly ; 



' Loc. cit., p. 125. 



