260 POLYZOA INFUNDIBULATA. 



funnel or bell, they will often remain quiet and apparently 

 immoveable for a long time, presenting a very pretty and 

 most interesting object to an observer of " the minims of 

 nature/'' If, however, the water is agitated they withdraw 

 on the instant, probably by the aid of the posterior ligament 

 or muscle ; the hinder part of the body is pushed aside 

 up the cell, the whole is sunk deeper, and by this means the 

 tentacula, gathered into a close column, are brought within 

 the cell, the aperture of which is shut by the same series of 

 actions. The polypes of the same polypidom often protrude 

 their thousand heads at the same time, or in quick but irre- 

 gular succession, and retire simultaneously, or nearly so, but 

 at other times I have often witnessed a few only to venture 

 on the display of their glories,, the rest remaining concealed ; 

 and if, when many are expanded, one is singled out and 

 touched with a sharp instrument, it alone feels the injury and 

 retires, without any others being conscious of the danger, or 

 of the hurt inflicted on their mate. 



The polypidom, formed in some species of a congeries of 

 many thousand cells, begins with one only. This original or 

 seminal cell has no sooner been completed, or even in many 

 instances previous to its perfection, than another begins to 

 shoot out from a fixed point of its parietes, the bud gradually 

 enlarging and developing itself until the form and size of the 

 primary one has been attained. This process can most easily 

 be traced in the Vesiculariadae, and in our common Flustrse 

 and Escharinse, where round the margin of the crust cells 

 can at all seasons be observed in every stage of their evolu- 

 tion ; one just jutting out, another half-formed, and others 

 again nearly complete. They never originate in the body 

 of the polype, but always from the parietes, or rather 

 the connecting medium ; nor indeed is the embryo distin- 

 guishable within until the cells have made considerable ad- 

 vances to maturity. Then the softer parts begin to assume a 

 shape, and gradually to limb themselves after the similitude 

 of their antecedent copartners, when, having reached their 

 term and ready for a partial independency, they burst their 

 outward cerements, always at a fixed point prepared for 

 their exit by the same Power which has moulded the whole. 

 From this mode of increase there would seem to be no 



