1885.] natural sciences of philadelphia. 97 



April 7. 

 The President, Dr. Leidy, in the chair. 

 Twenty persons present. 



The Primary Conditions of Fossilization. — Mr. Charles Morris 

 made a communication in answer to the query : " Why are there 

 no fossil forms found in the strata preceding the Cambrian ? " In 

 mineral conditions there is little difference between the two sets 

 of strata. Yet the Cambrian contain numerous fossils, while 

 the preceding strata are barren in this respect. This Cambrian 

 life, however, does not come in the succession we might naturally 

 expect, and it ma}' be desirable to consider the succession which 

 actually occurs. 



Of Protozoa there is not a trace, if we reject the doubtful 

 Eozob'n. Yet vast numbers of Protozoa must have existed, and 

 if there were any calcareous- or siliceous-shelled forms, as at 

 present, they must have left some indication in the rocks. The 

 Metazoa do not begin with the lowest forms, but the different 

 orders make their appearance in very odd conjunction. Thus, at 

 the very beginning, we have a great variety of tribolites, in con- 

 junction with a much smaller variety of annelides and mollusks, 

 while there are very scanty traces of sponges, echinoderms and 

 the lower crustaceans. The most advanced form of these animals, 

 the trilobite, greatly outnumbers all its contemporaries. 



At a considerably later date two widely separated forms come 

 together into existence. The low order of Hydrozoa makes its 

 first appearance as the Graptolite, and at a closely related date 

 appear Cephalopods, the highest order of Mollusks. The Silurian 

 era opens with an abundance of Graptolites and a considerable 

 increase of Cephalopods. It is much later ere any clear trace of 

 Vertebrates appears, and this in what is certainly not their lowest 

 form. 



The appearance of land animals presents a somewhat similar 

 phenomenon. No land Vertebrates appear below the Carboniferous 

 rocks, yet it is now known that insects existed well down in the 

 Silurian, proving that the conditions necessary for land life had 

 very long prevailed ere Vertebrates left the sea for the land. 



It is impossible to believe that these fossils represent truly 

 either the beginning or the actual succession of life upon the 

 earth. Such an idea would be utterly inconsistent with the 

 development theory, and even under the creation hypothesis it is 

 incredible that life could have begun with such a confused mixture 

 of high and low. No one, for instance, can accept what the rocks 

 seem to teach, that advanced forms of Mollusks and Crustaceans 

 came into existence before the Ccelenterata. It may be taken for 



