The Catopterus gracilis. 



By Chas. H. S. Davis, M. D. 



There is an enormous series of subaqueous sediment, originally 

 composed of mud, sand or pebbles, the successive bottoms of a 

 former sea, and in which no trace of organic life has yet been de- 

 tected. 



These non-fossiliferous sedementary beds form, in all countries 

 where they have been examined, the base-rock on which the Cam- 

 brian or oldest Silurian strata rest. 



Whether they be significative of ocean abysses never reached by 



the remains of coeval living beings, or whether they truly indicate 



the period antecedent to the beginning of life on this planet, are 



questions of the deepest significance, and demanding much farther 

 observation before they can be authoritatively answered. 



PaljEontologists fail to detect a single bone of any aquatic ani- 

 mal of the vertebrate class in rocks older than the uppermost divis- 

 ion of the Silurian system, but fishes are found in all the great 

 rock foundations from the graywacke upward, and, therefore, the 

 history of fossil fishes becomes of great importance. 



When we consider how rich a molluscuous fauna, to say nothing 

 of the crustaceans, sea urchins, corals, etc., which have been met 

 with in almost all parts of the world, it seems impossible to account 

 for our not having yet found any accompanying bones of fish, ex- 

 cept by supposing they were not yet in being, or that they only 

 occupied a limited area. 



Next to the Silurian comes the Old Red-sandstone Devonian 

 formation, which is very rich in fishes, the majority of which be- 



[The Association is indebted to Messrs. Ivison, Blakeman & Taylor, the pub- 

 lishers of Dana's Geology, lor the use of the cut of the Catopterus gracilis. '\ 



