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 | | The gasteropods now developed all the leading types of shell (Pleurotomaria, Omphalotrochus) ; but both this class and the pelecypods (Lyrodesma, Ctenodonia, Modiolopsis) were subordinate in importance to the cephalopods. |
 | | These mollusks were probably the most powerful living creatures in the Ordovician seas; straight-shelled, slightly curved, and nautiloid forms predominated (Orthoceras, Cyrtoceras, Gyroceras, Trocholites, Endoceras, Litoceras, Lituites, Actinoceras). |
 | | Some of the straight shells were of enormous size, 12 to 15 ft. long and as much as 1 ft. in diameter, in the widest part. |
| encyclopedia.jrank.org /correction/edit?locale=en&content_id=49785 (1782 words) |
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