198 KANSAS CITY REVIEW OF SCIENCE. 
died out. As degradation to a lower character is a part of the theory of evolu- 
tion, here is just the change of surroundings which should have given us a lower 
species. 
The same modification and local extinction took place in the eatable cockle, 
mussel and periwinkle (Cardium edule, Mytilus edulis, and Littorina Littoria), 
which are also found in the ‘‘refuse heaps.” They, as well as many species not 
eaten by man, and now flourishing in the adjacent North Sea, became stunted 
and disappeared in the same gradual manner, without any specific change. Others. 
more hardy are now living in both seas, but are much smaller in the Baltic than 
in the North sea, yet showing no loss of characteristic traits. 
If we examine the Ammonites, we shall find a tribe which varies in its 
characteristics more, probably, than any other mollusk. They appear in the 
Devonian, and continue to the Eocene Tertiary, or during one-half of the whole 
geological period. They are represented by more than one thousand species. 
This great number presents quite a diversity, showing that the family possessed what 
is called a protean tendency in size and shape. It is claiined by some paleontol- 
ogists, with some show of facts, that many of these species run into, or are 
derived from others. It is even contended that genera of the family can be 
traced from one to another by gradual variation. This is not yet admitted by our 
leading authorities in paleontology. Notwithstanding the marked variance of 
different species, they are all distinguished by common characteristics, viz., a 
chambered shell with sutural or interlacing partitions, and a siphuncle passing, 
not near the center, but along the side of the chamber, through the partition. 
The variations of structure are always confined within the circle of these condi- 
tions. The thousand species are during this long range of time not only Ceph- 
alopods, but restricted to the narrow limits of their family features without 
crossing its boundaries. ‘There is no proof that they were derived from a lower 
type or passed to a higher. | 
Now if we allow the utmost claim of the evolutionists, that all these species 
and genera sprang from one common stock, even then we may say, the change 
is too small relatively, to show that any truly low type evolves to a higher. Had 
they continued to live to the present age, would they, at the same rate of prog- 
ress, have attained the structure of a low crustacean? The great variety of forms 
are in most cases no increase in rank, but simply in diversity from those asso- 
ciated in the same seas. 
The firm continuance of general features, from the Devonian to the Tertiary, 
is much stronger against a general system of evolution than the variance of form 
is in its favor. Is it not more remarkable that during so long a geological term, 
in all parts of the world, under so great a diversity of circumstances, that there 
should have been so little change rather than so much. 
The Nautilus family presents another somewhat similar history. It appears 
in the Lower Silurian Age and continues to the present day, through almost the 
whole of earth’s geological history. The Nautilus resembles the Ammonite, but 
