194 The Naturalist of Cumbrae. 



contained marine villa. Sabellaria, on the contrary, 

 forms a colony of greater or less extent, each indi- 

 vidual tube being joined to its neighbour, and so 

 forming an extensive terrace, with fine crescents of 

 self-contained houses. Each annelid has a double 

 plume of golden-coloured bristles, and when, again 

 covered by the advancing tide, each looks out at its 

 own door, the reef must present a scene of great beauty 

 from the metallic brilliancy of their coronets." 



It would have been interesting to quote the whole 

 of the account, but that Mr. Robertson disclaims 

 having done more than observe with admiring eyes 

 the scene of which his friend Dr. Grieve penned the 

 description. In a subsequent paper, also of great 

 interest, " On the Luminosity of the Sea," by Messrs. 

 David Robertson and William Keddie, Robertson, it 

 will be observed, was the senior partner. 



At a conversazione of the Natural History Society, 

 held on November 24, 1863, the secretary, Mr. Robert 

 Gray, gave a short sketch of its history, plans, and 

 progress, in the course of which he thus alludes to, 

 without the necessity of naming, Mr. Robertson : 



" In the marine section, the society refers with much 

 satisfaction to the successful labours of one of its 

 members, who, by his own unaided efforts, has opened 

 up, in a remarkable degree, the zoology of the Firth 

 of Clyde. Many animals, hitherto accounted rare, 

 are now known to exist as common objects, while the 

 ..annals of science have received many important 

 additions of animals altogether new to natural history 

 records discoveries which have caused the Firth of 

 Clyde, and more particularly the Cumbrae Islands, to 



