106 ' ZOOPHYTES. 



it is very singular, that after the hydra has quite wasted away and disap- 

 peared, four included ova should be tossed about in the distended integu- 

 mentary prominence remaining. 



Possibly the ovum ripens as the hydra decays. I have conjectured, 

 that some peculiar aperture about the root of the tentacula, allows the 

 previous escape of the earliest, which are matured during summer ; but 

 later in the season, I cannot find that they are liberated otherwise than 

 by decay of the body. 



As autumn advances, and particularly during Sej)tember or after- 

 wards, the number of hydra; protruding from the stratum decreases, while 

 the number of ova escaping increases. Thousands are at length freed by 

 supervening decomposition, and rise above in groups on the water, or form 

 a complete internal belt around their vessel at the surface. 



The ovum of the Alcyonella is lenticular, like that of the Cristatella, 

 but not a fifth part of the size. Its surface is smooth and shining, and 

 the arrangement of the colours inverted, compared with those of the latter, 

 the middle being yellow, and a broader zone brown. There is no circum- 

 ferential row of hooked spines or other processes present. As the ovum 

 rises to float after liberation, the observer must then beware of deception 

 from its apparent elliptical, instead of its true, circular formation. — Fig. 9. 

 This delusion is often very strong, insomuch that it is difficult to reject its 

 impression. The dimensions of the ovum will not admit an investigation, 

 whether the obliquity of its position results from some internal aerial re- 

 servoir appropriated for the use of the embryo, until enabled to subsist on 

 liberation by maturity. 



A long time elapses, not less than 167 days, in perfecting the con- 

 tents of the ovum, when those of the preceding season are hatched during 

 the subsequent April, May, or June. Each ovum then sunders like the 

 former — that of the Cristatella — to allow the protrusion of a shapeless 

 substance, which is gradually moulded as a symmetrical hydra. — Fig. 10. 



The hydra has attained considerable size against the time the halves 

 have completely separated, and it is then that its structure is best exposed. 

 But the number, proportions, and arrangement of the tentacula, now 

 scarcely exceeding 20, are of future evolution and modification. Let us 



