Tlie Fauna of the St. John Group, 



361 



the Primordial Fauna are a means of bringing before our 

 mental vision a conception of what that fauna may have 

 been. Dr. Henry Hicks has surmised that the Cambrian 

 Fauna came from the central region of the North Atlantic 

 Ocean, invading the continental margins on each side of 

 the oceanic area ; but whatever its origin, it would appear 

 that the fauna reached Europe and America by independent 

 routes, if we may judge by the representative species present 

 in the two continents. 



The following is a rough estimate of the number of 

 animals in the several orders which have so far been 

 found in Division I. of the St. John Group ; it shows that 

 the fauna is thoroughly representative of the earliest 

 Cambrian stage, being characterized by the great prepon- 

 derance of the trilobites over all other forms, and by the 

 prevalence of brachiopods with horny shells. This list is 

 not to be regarded as final. 



Classes and Orders of Animals in Division I. 



Rhizopoda (Sponges, &c.) 



Hydrozoa (Graptolites, &c.) . . . 

 Echinodermata (Cystidians) . . 

 Brachiopoda (Lamp shells, &c] 

 Pteropoda (Sea butterflies, &c.) 

 Gasteropoda (Sea snails, &c ) . . 

 Crustacea (Crustaceans) 



Order Phyllopoda . 

 " Ostracoda . . 

 " Trilobita ... 



Genera. 



14 



Species 



3 



4 



28 



35 



Var. 



14 



14 



Genera. 



3 

 2 

 1 

 6 

 2 

 2 

 14 



30 



Species. 



3 



2 



1 



12 



5 



7 

 35 



65 



Varieties 



2 



4 



14 



21 



The appearance and disappearance or extinction of the 

 genera and species composing the above fauna is shown by 

 the following statement of the composition of the sub- 

 24 



