DEVONIAN PERIOD 47 



much into vogue, either in this Period or afterwards, its 

 advantages must have been more apparent than real. 



Cystids were fast dying out. However illustrious in the cystids 

 past as the stock from which " sea-lilies " and blast oids had 

 come, their glory had now quite departed. They were 

 destined, however, to Unger on for a time, but with an ever- 

 diminishing horizon. 



On coral reefs the colonies of honey-comb appearance corals 

 (Favosites) were still conspicuous ; and new colonies — also 

 with zooids of the more social kind — were becoming impor- 

 tant as reef -builders {Phillipsastrcea). The less social chain- 

 coral colonies, prominent on Silurian reefs, had now become 

 extinct {Haly sites). 



Calcareous sponges, that is, sponges with needles or spicules sponges 

 formed of carbonate of lime, now come into view for the 

 first time. They continued very few in number during the 

 Period as compared with sponges with flinty skeletons, and 

 their needles were smaller and less varied than those of the 

 latter. Calcareous sponges never discarded needles, and con- 

 sequently have always enjoyed some immunity from sponge- 

 eating animals. 



The land population was not of much higher character 

 than in Silurian times ; but there were some notable appear- 

 ances. Myriapods, with resemblance to certain millepedes myriapods 

 of our own day, and descended from annelid sea- worms, 

 were now abroad (Archidesmus, Kampecaris). Large-winged 

 insects, allied to may-flies, were flitting about (Lithentomum) ; insects 

 and rough music was to be heard ; for some of the number 

 had wings adapted for emitting a scraping noise {Xenoneura). 



Doubtless there were many other forms of insects of 

 which no evidence has been discovered. For insect-hfe during 

 this Period must have been stimulated into a varied evolution 

 by the development of plant-life ; and may indeed have 

 rendered reciprocal services. 



Vegetation retained many old features, but some important vegetation 

 developments were in evidence. Certain cHmbing growths 

 of ancient origin, and combining afftnities with club-mosses, 

 "horsetails," and ferns, were prominent, but were not 

 developing sufficient stem-strength to stand alone (Spheno- 



