viscous substance while alive, and in many cases to have 

 struggled hard to escape, as is evident from the legs and wings 

 which are frequently found separated from the bodies to which 

 they once belonged. 



The development of many types of the Animal Kingdom 

 is progressive, the most simple appearing first. Thus the 

 earliest Vertebrates were Fish. Batrachians and Reptiles appeared 

 on the stage of life next in succession, and Birds were followed 

 by the Mammalia. This was equally the case with the Inverte- 

 brates. The Crustacean is inferior to all the other sections of 

 the Order Arthropoda, which includes the Arachnida and Insects. 

 The Trilobites are the most remarkable of the Order. After 

 their first appearance in the Palaeozoic age they soon 

 broke up into a multitude of genera (no less than 140), 

 buf not a single representative survived to the Mesozoic age. 

 The insects whose metamorphosis was incomplete, preceded that 

 which was complete, and thus had advanced a step. The 

 Lingulae and Discinse have remained without any sensible 

 modification since Palaeozoic times, the Terebratulae of the 

 present day scarcely differ from those of the chalk. Crustaceans 

 are now found in the profound depths of the seas which recall 

 to mind the Jurassic Eryon, beautiful examples of which are 

 found in the Lithographic beds of Solenhofen (Kimmeridge). 

 Representatives of this interesting family are met with as early as 

 the Trias. Thus every fresh discovery tends to corroborate the 

 view that animals with which we are familiar have been gradually 

 modified from pre-existing forms, following each other in a regular 

 sequence and showing that the progress usually is from the 

 general to the special. Some of the highly specialised forms 

 even of the early periods became extinct, having reached the 

 limits of further development. 



Faunas and Floras have passed on in succession from one 

 geological age to another, and the beds in which they are 

 entombed can be classified on a plan corresponding to those 

 changes. In each some new species and genera appear for the 

 first time, which did not exist in the preceding one. This 



