BRITISH NULLIPORES. 237 



even showing a disposition to throw up any shoots : when 

 germinating in deep water, the growth is likewise arrested 

 and we have lobed or sinuous masses of different densities 

 and figures, deriving their peculiarities from those of the 

 ground they grow upon, and from the state of the water above 

 and around them ; and if the coralline has begun its growth 

 on a flat rock where it lies much uncovered by the tide, and 

 open to the sun's influence, it remains for ever a compara- 

 tively soft white porous leprous crust, — the Millepora co- 

 riacea of some authors. The life of the coralline is too 

 retentive to be destroyed by these influences, and it evi- 

 dences its continued existence by efforts which result in 

 bastard monstrosities. 



SchvVeigger asserts that he has traced the Ulva squamaria of Gmelin 

 passing into the Millepora coriacea of Linnaeus. (Beobaeht. p. 46-7, 

 tab. 4, fig. 25-30 : Handb. p. 438.) The figure which he has given of 

 the Ulva seems to me to represent very well the Zonoria deusta or Po- 

 dina deusta of British botanists, the true position of which has puzzled 

 the most learned algologists. It is, says the Hon. Mr Harvey, " a very 

 anomalous plant, of very uncertain affinities. I leave it in Padina mere- 

 ly because it has been placed there by others, and that I know not to 

 what other genus it is more nearly allied. Its resemblance to Padina is, 

 however, merely superficial ; its structure is totally distinct, and is not 

 even dictyoteous." (Man. Brit. Alg. p. 31.) The observations of M. 

 Schweigger throw light on this question ; and those which I have made 

 on the Zonaria, where it grows abimdantly on the slaty rocks in front of 

 the coves of Holy Island, have led mc to think that the opinion of 

 Schweigger is very probably true. The Zonaria and a crustaceous Mil- 

 lepore, evidently identical with the M. coriacea of Schweigger, grow there 

 intermingled, similar in habit and mode of growth, and with a similar ve- 

 getable basis ; but although I have found specimens in contact, I cannot 

 say that I ever saw any which were exactly intermediate. 



