NATURAL HISTORY SOCIETY OF GLASGOW. 31 



the mass of sand. The margin is quite thin and easily broken, 

 crushing under the foot. On such an exposed position one 

 woukl suppose them to be often buried, from the shifting nature 

 of all sandy bottoms, but there was no appearance of any 

 recent calamity, the margins of the tubes being all quite perfect. 

 This annelid is the Sabellaria alveolata. It is nearly allied to 

 the Pedinaria JBelgica, commonly found on our sandy coasts, each 

 individual of which lives in a single tube formed of grains of sand 

 — a self-contained marine villa. Sabellaria, on the contrary, forms 

 a colony of greater or less extent, each individual 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. 

 This reef, in extent about 50x20 feet, interested us exceedingly. 

 The Sabellaria we had not previously seen, and so vast a multitude 

 our reading had not led us to exj^ect. But on rounding the head- 

 land, and finding that for half-a-mile the whole shore was tenanted 

 by them, and the loose boulders, which became more numerous as 

 we receded from the precipitous point towards the pier at Stair- 

 haven, were all filled up by the sand driven among them, and, 

 though worn into numerous pools, completely cemented and bound 

 together by these annelids, our admiration was still more excited. 

 It was a sand reef, formed by annelids, analogous, so far, to a coral 

 reef formed by zoophytes, yet, of course, differing as to formation, 

 the coral, or carbonate of lime, being secreted by the zoophyte, 

 while the free shifting sand is only agglutinated by the sabellaria. 

 When the animals are dead, and the sand becomes dry, we have 

 found it very friable. Allotting four individuals to every square 

 inch, some idea may be formed of the immense multitude in the 

 half-mile over which we walked. 



Tlie following list of mollusca, found in the Bay of Luce, was 

 furnished by the Eev. A. Urquhart, Portpatrick. A f is affixed to 

 those obtained by us : — 



Mya truncata, Not uncommon. 



t — arenaria, „ 



Ceratisoleu legumen, .... Rare. 



fSolen siliqua, Common. 



t — ensis, „ ■ 



