ORDOVICIAN PERIOD 



27 



became important animals not only in the sea, but in fresh 

 water also. 



Marine life, it will be noted, was for the most part strong 

 in defence ; and various animals of active and aggressive 

 habits of which nothing is known may well have been in 

 the seas. Fish-like forms were possibly coming to the fore, 

 but there is no satisfactory evidence as to this. If as is 

 likely they were already in existence, they were probably 

 backboneless and soft-bodied, and had, therefore, no enduring 

 " wrack " to leave behind. 



On land, primitive " horsetails " (Protannularia) and club- VEGETATION 

 mosses (Protostigma) were extending their range. Other 

 verdant forms bearing mostly wedge-shaped leaves seem 

 to have been combinations of these, and to have held, more- 

 over, affinities with ferns (Sphenophyllum). Insects were INSECTS 

 certainly about the scenes (Protocimex). These creatures 

 were well-winged, and appear to have been a species of the 

 bug order (Hemiptera). Their presence leads one to suppose 

 that various insects of lower grade, especially wingless forms, 

 were already in existence. Many of them by this time may 

 have quite forsaken the waters, where their ancestors 

 probably minute crustaceans had long dwelt and prospered. 



