36 



SEA PLANTS, CORALS, ECT. 



mean organization and ferocious habits, of which the shark 

 and sturgeon are living specimens. " Some were furnished 

 with long palates, and squat, firmly-based teeth, well 

 adapted for crushing the strong cased zoophytes and shells 

 of the period, fragments of which occur in the f cecal re- 

 mains ; some with teeth that, like the fossil sharks of the 

 latter formations, resemble lines of miniature pyramids, 

 larger and smaller alternating ; some with teeth sharp, 

 thin, and so deeply serrated, that every individual tooth 

 resembles a row of poniards set up against the walls of an 

 armory ; and these last says Agassiz, furnished with wea- 

 pons so murderous, must have been the pirates of the peri- 

 od. Some had their fins guarded with long spines, hooked 

 like the beak of an eagle ; some with spines of straiter and 

 more slender form, and ribbed and furrowed longitudinal- 

 ly like columns ; some were shielded by an armor of bony 

 points, and some thickly covered with glistening scales."* 



The traces of fuci in this system are all but sufficient 

 to allow of a distinction of genera. In some parts oi 

 North America, extensive though thir beds of them have 

 been found. A distinguished F»*-:icn geologist, M. Brog- 

 niart, has shown that all existing marine plants are classi- 

 fiable with regard to the zones of climate ; some being 

 fitted to the torrid zone, some for the temperate, some for 

 the frigid. And he establishes that the fuci of these early 

 rocks speak of a torrid climate, although they may be found 

 in what are now temperate regions ; he also states that 

 those of the higher rocks betoken, as we ascend, a gradu- 

 ally diminishing temperature. 



We thus early begin to find proofs of the general uni- 

 formity of organic life over the surface of the earth, at 

 the time when each particular system of rocks was form- 

 ed. Species identical with the remains in the Wenlock 

 limestone occur in the corresponding class of rocks in 

 the Eifel, and partially in the Harz, Norway, Russia, and 

 Brittany. The situations of the remains in Russia are 

 fifteen hundred miles frormthe Wenlock beds ; but at the 

 distance of between six and seven thousand from those — 

 namely, in the vale of Mississippi, the same species are 

 discovered. Uniformity in animal life over large geogra- 

 phical areas, argues uniformity in the conditions of ani- 

 mal life ; and hence arise some curious inferences. Spe- 

 cies, in the same low class of animals are now much more 

 * Miller's " New Walks in an Old Field." 



