ROBERTS — UPPER SILrPJAX CORALS. 



55 



UPPER SILURIAN CORALS. 



A SKETCH BY 



GEORGE C. ROBERTS. 



CoRAL-HUXTiXG in the deliris of a Wenlock-sliale qnarry ranks high — 

 to my ttdnMng — amongst the pleasures of geology. And, indeed, 

 has no insignificant place among its wonders. For to any one not 

 conversant with zoophytic Hfe, it is hard to beheve that the rugged 

 corals that lie strewn about the quarry, once held sensitive masses of 

 life — that from every pore tiny arms waved to and fro in the water 

 to entangle the lesser creatures they hved on ; and that the animal — 

 that shght thread of jelly-like substance, filling each tube, was at 

 once a limb of the body and an independent creature, contributing, 

 while attached, to the general support, and being able, if severed 

 from the mass, to lead a separate existence and be itself the parent 

 of others. The Wenlock series of the Upper Silurians have been 

 rightly regarded as the meti^opolis of its zoophytic life, for both in 

 variety and number, corals culminated in the seas of that age. Of 

 these species, " so far removed from existing ones as to be quite 

 unknown in modem seas, all, with rare exceptions, dying out at the 

 close of the Palaeozoic epoch."* I will essay a familiar sketch. 



I adopt the nomenclature of M. Milne Edwards, whose valuable 

 memoir of Silurian corals, published by the Palasontographical So- 

 ciety, is my guide and instructor. 



True corals are called by zoologists Zoantharia ; and those with 

 which we have now specially to do belong to the order Anthozoa. 

 They have again been divided into cup-, and star-corals — Zoantliaria 

 rugosa, and millepores — Z. tahulata. The first division may either be 

 simple — tenanted by a single polyp, or compound — the result of an 

 aggregation of polyps, the latter, as its name implies, must always be 

 the shelter and defence for a community. The animal itself was a 



* « Siluria," 3rd edition. 



