366 PROF. EHRENBERG ON ANIMALS OF THE CHALK 
the more decidedly different all the creatures of that period were 
from those of the present time ; but loses more and more in im- 
portance the less the chalk proves to be a chemical precipitate, 
and the more numerous the forms agreeing with those of the 
present day become by renewed inquiry Nay, there is not the 
least doubt that the perfectly ascertained identity of a single 
species of the present day with one of those of the chalk, ren- 
ders doubtful the necessary transformation of all the others sub- 
sequently to the formation of the chalk rocks; how much more 
so when these are numerous, and such as form masses! The 
size appears to be of no importance, as the small organisms 
have already been shown to agree with the large with regard to 
the effect of external influences upon them. 
7. The period of the dawn of the organic creation coexistent 
with ourselves, can only be admitted as being anterior to and 
below the chalk formation, if indeed, which is questionable, such 
a distinction can be made; or the chalk, with its rocks, co- 
vering far and high the superficies of the earth, forms part of the 
series of recent formations, and, since of the four as yet well- 
established great geological periods of the earth’s formation, the 
quaternary, tertiary and secondary formations contain recent or- 
ganisms, it is as three to one more probable that the transition 
or primary formation is not differently cireumstanced, but that, 
from the gradual longer chemical decomposition and change of 
many of its organic relations, it is more difficult to examine and 
determine. 
Paludina vivipara and Cyclas cornea of the Weald clay, and — 
the recent Trochus below the chalk, according to Defrance, as — 
well as the confirmation of the occurrence of Terebratula Caput 
Serpentis in the upper Jura by Von Buch, together with my 
observations of microscopic yet nevertheless peculiar Polytha- 
lamia in the flints of the Jura, are additional positive indications 
of the inconceivable extent of similar organic relations, the fur- 
ther investigation of which is one of the important questions to — 
be determined i in the present age. 
. It cannot be denied that the notion hitherto frequently as- 
net that all recent organisms, including man, are the descend-— 
ants and perfected stages of metamorphoses of Trilobites and | 
Ferns, has something in it opposed to sound sense ; when there- 
fore the direct inquiry leads powerfully to a different point of 
view it has much in its favour, even though it be reserved to a 
future period to explain the vast connexion of the phenomena. 
sa me ny en 
