LOBULARIA. 179 



imperceptibly to either side, or slight curvature over the common basis. 

 The hydra? are leisurely evolved, and gradually retracted. 



The superficies of the basis is smooth, and close to the place of adhe- 

 sion, very like leather ; its substance porous, the pores larger as lower, 

 tending to an oval form, and separated by thin parietes. 



It needs scarcely to be explained, that no hydra? belong to the smooth 

 or to the lower portion. 



Contact with the Lobularia imparts a most nauseous odour to the 

 hands, of which they cannot be easily divested. 



The Loblllaria is either of fine rich orange colour, or white as snow. 

 It is not easy to pronounce which of two luxuriant specimens, with the 

 numerous hydra in full display, shall he deemed the more elegant. Both 

 are beautiful. 



No difference of species is indicated by so striking a diversity of colour. 

 On one valve of a very large mussel, an ample white Lobularia, with 

 eleven or twelve extremities, was seated ; the other valve sustained an 

 orange specimen, about half the size, with six or seven. Both were in ad- 

 mirable perfection. Farther, two Lobulariae adhered to the shell of a Tri- 

 tonium undatum, the one orange, four or five inches high, the other white, 

 in immediate proximity. A white specimen, between two of orange colour, 

 occurred on a third occasion. 



Circumstances have induced me to conjecture that the white colour 

 might be converted to orange. But I cannot say that this has been con- 

 firmed by actual observation. 



The colours distinguishing each specimen are not superficial ; they 

 belong to the whole, penetrating from the surface to the centre. If the 

 surface be white, the centre is white ; if the surface be orange, so is the 

 centre ; at least such is almost invariably the case. 



Nevertheless some peculiarities should be noted. 



The Lobularia propagates by means of ova, which I have never seen 

 unless of an orange colour. These ova are generated below, and approach- 

 ing maturity, rise towards the surface, like those of some other zoophytes 

 already described. On November 3, several specimens of the Lobularia, 

 all white, reached me from the Mar Bank. They invested the tube of the 



