TINY ROCK-BUILDERS. 



149 



Wenlock, and more particularly at what is called 

 the Wren's Nest, near Dudley, numerous kinds of 

 corals may be hammered out, among them being 

 Omphyma, Forties, Heliolites, the " chain-coral " 

 (Holy sites), Cyathophyllum, and others. When 

 this luxuriance of sub-tropical life is compared with 

 the few species of our warmer Devon and Cornish 

 coasts, the largest 



phyllia, some idea 

 can be formed of 

 the vast changes 

 which our climate 

 must have under- 

 gone since those 

 remote epochs 

 when coral is- 

 lands and coral 

 reefs occupied the 

 site of Britain. 

 In the quarries 

 round about 



Church Stretton, too, I have found enormous 

 quantities of corals. In this region, made classic 

 by Sir Roderick Murchison's Siluria it is difficult 

 to find a Silurian section without several kinds of 

 coral being seen. The common Cyathophyllum, 

 the " petrified ram's horns " of the quarrymen, as 

 well as Heliolites inter stinctus, which gets into 

 every cabinet of fossils, are abundant. A figure 

 of the latter is given (Fig. 37), and also a magnified 

 portion (Fig. 38), which will illustrate the corallites, 



FIG. ^1. Heliolites interstinctus. 



