GEOLOGICAL EXTERMINATIONS. 



177 



easily succumb, and the smaller animals that have the greatest 

 chance of escape. 



Then with regard to the Quaternary period, Mr. Warring seems to 

 be again in error. The Quaternary period is that in which we are 

 now living. There cannot be any distinction drawn between the 

 latest or Quaternary deposits and those of to-day ; man goes back in 

 time through all the Quaternary period, and the animals we see 

 to-day belong to the Quaternary period also. 



Then with regard to size, I must say that the author seems to be a 

 little in error. The larger land animals were the huge land-reptiles, 

 the Dinosaurs, and they lived between the Trias and the Chalk 

 periods. There was during the Chalk period a great terrestrial 

 extent of the earth's surface exposed and habitable and whose 

 animal remains are found in old lake-deposits, not in marine beds 

 like our chalk. There were large tracks in America where animals 

 of huge size dwelt, and among them were those reptiles, the 

 Dinosauria. They all died out at the end of the Chalk period. 



Take again the great group of fishes, for instance; they commenced 

 in the Silurian, and forms resembling some of those living to-day are 

 found in Devonian rocks. Sharks occur in the Devonian, and forms 

 of scaly fishes. The principal difference is that the fish of to-day 

 usually possess a strong bony skeleton, whereas in the earliest fishes 

 there was no hardened skeleton — they were notochordal, having 

 only a gelatinous or cartilaginous skeleton ; many also had a covering 

 of hard armour plates. Some of the cartilaginous fishes (e.g., the 

 sharks) are living to-day. 



With regard to the birds, they appeared first in the Jurassic 

 period, and the earliest possessed teeth, but they were clothed with 

 feathers ; they were not reptiles. We have never found any other 

 animals, save birds, that possessed feathers. Then in the London-clay 

 period more birds appear, some with serrated jaws (not true teeth) 

 and some with long horny bills, like grebes and Solan geese, well 

 adapted for catching fish, so that modern birds really may date from 

 the Eocene period, and they have thus a long historical record. 

 Mammals were supposed to begin in the Trias and go on to the 

 present day, but the remains found in the Trias probably represent 

 Ammodont or Theriodont reptiles that had some affinity towards 

 mammals, but were not really mammals at all. In the Purbeck 



