11 



of the pianae and stems are raptured, the central pulp is 

 aiways partially, and frequently wholly expelled. liovv 

 can these phenomena be satisfactorily explained, but by 

 supposing the existence of irritability and pressure in the 

 sheath ? I have never obtained traces of vascularity, but 

 different sections of the trunk prove that some kind of action 

 is going on there. If a cross section of a stem be taken from 

 a )oung part, it will be found of light texture and of equal 

 consistence throughout; if lower, to be harder and darker, 

 especially towards its inner margin, and so in gradation to 

 the roots, where it will be found of a hard and somewhat 

 brittle consistence throughout. The younger parts may be 

 bent with safety, while the older portions are more rigid and 

 can be bent only at the risk of breaking. From these facts, 

 it appears to be the most philosophic to consider the poly- 

 pidom as endowed with vitality and as forming with the 

 polypes and pulp the entire animal. 



Several species that grow near low water mark, will 

 sometimes emit sparks of light wben gently agitated, and 

 this is greatly increased, if the water be gently heated. 

 This is frequently the case with Sertularia pumila, and 

 appears to arise from minute Entomastraca and Macakphce 

 which so constantly infest them. 



The order is divided into three Families which contain 

 eleven Genera; and examples of each, exeept the fresh 

 water polype, are common on all parts of our coast. Indeed 

 so rich are we in these beautiful productions, that the 

 majority of those recognized as British are to be found in 

 our seas. The Generic differences, will be found at large in 

 their proper places in the following pages, where their 

 species are described, and need not therefore be given here. 

 A summary of the whole will be found at the end, drawn 

 up without reference to the polype, to suit the convenience 

 of those who are not iatimately acquainted with the 

 subject. 



TUBULARIAD.E. 



Polypes gemmiparous, the gemmules naked, pullulating 



from the base of the tentacula. 



CORYNE, Gaertner. 



Generic Character: Polypes fixed, single, naked, cylindrical 

 or claviform, but contractile, the head with scattered fili- 

 form smooth tentacula, mouth none ? 



C. SQUAMATA. Body more or less clavate; the tentacula 



shorter than the body. 



Tubularia affinis, Turton's Lin., vol. 4, p. 660. Stewart's 

 Elera,, vol. 2, p. 438. Coryne Squamata, Fleming's Brit. 

 An., p. 553. C. Multicornis, Templeton in Mag. of Nat. 

 Hist., vol. 9, p. 419. Johnston's Brit. Zooph., p. 109, pi. 2. 



