76 



SKETCHES OF C BE AT I ON. 



tological discoveries. An assemblage of strata named by 

 him the "St. John's Group" is described as underlying 

 rocks that had heretofore been regarded as forming the 

 very base of the Silurian system in America. These St. 

 John's strata may probably be regarded as inclosing the 

 remains of the first considerable fauna that ever lived 

 within the limits of America. Our knowledge of these 

 primeval relics is as yet very imperfect*, being limited to 



one crinoid,tw T obrachiopods, 

 and half a dozen genera of 

 trilobites. Though they mark 

 generally a great simplicity 

 of organization, one can not 

 but be astonished that in the 

 very outset of animalization 

 upon our globe so high a 

 rank and so great variety of 

 types should have been man- 

 ifested. If we are to judge 

 from that which is known 

 rather than that which is con- 

 jectured, we are compelled 

 to conclude that the varied 

 forms of animal life did not 

 come into being by a gradual 

 evolution from the Eozoon, 

 but as so many original ut- 

 terances of the all-skilled Ar- 

 tificer of creation. 

 Of the " Potsdam group" of strata [see Appendix, Note 

 III.], and the organic remains which they inclose, we have 

 learned somewhat more. The " Potsdam sandstone" at the 



Fig. 21. Paradoxides Harlani (X%). St. 

 John's Trilobite. 



* Billings (E.): 

 Anticosti," p. 79. 



Catalogues of the Silurian Fossils of the island -of 



