228 Proceedings of the 



maceration in fresh water. The tentacles, from four to about 

 forty in number, according to the age of the polyp, are ar- 

 ranged spirally in several rows round the buccal papillae. 

 Thick at their insertion, they decrease in diameter towards 

 their extremity, and are extended, with a tendency to droop at 

 the points. Immediately beneath the lower tentacles, the re- 

 productive capsules hang in many-pedicled clusters, so that 

 this graceful zoophyte presents a resemblance to a miniature 

 forest of cocoa-palms heavily laden with fruit. 



4. Clava membranacea (Figs. 2 and 3). — In this species, 

 found at Queensferry, the polyps are closely massed together 

 in clusters, each cluster being either a male or female zoophyte. 

 The animal was found adherent to fronds of Fucus vesiculosus, 

 but so slightly, that the whole cluster could be readily de- 

 tached by peeling it off with the point of a scalpel. The 

 polyps had a rich aurora tint, and were larger and more slen- 

 der than those of Clava repens, some of them being more than 

 an inch long. The upper surface of the corallum, examined 

 after the removal of the polyps by maceration, presented the 

 appearance of a favoid aggregation of cells, closely cemented 

 together by an excessive development of the " colletoderm." 

 The cement between the cells included several species of dia- 

 tomacese and microscopic algge. The lower surface of the 

 corallum consisted of a mat of parallel and anastomosing tubes 

 of soft membrane. These tubes also passed beyond the cluster 

 of cells which they supported, and crept along the surface of 

 the fucus in irregular lines, to furnish, as it were, other colonies 

 of polyps. 



5. Clava corneals a clustered and dioecious zoophyte, resem- 

 bling in appearance the species last described. The speci- 

 men which I place on the table was kindly lent me, for this 

 evening, by my friend Mr Goodsir, and is one of the results of 

 his trip to the Orkneys with the late Professor Edward Forbes. 

 The polyps are long and slender, like those of Clava mem- 

 oranacea. The corallum apparently consists of a thin chiti- 

 nous plate attached to the fucus. Over part of this plate the 

 chitine rises in low, smooth ridges, running either parallel to 

 each other in winding lines (fig. 4), or meeting at various angles. 

 These ridges have a double contour under the microscope. 



