4 HYATT ON THE TERTIARY SPECIES 



they had been thoroughly studied. The small size of the third sieve of the sifter also 

 secui^ed a very thorough examination of the sand, so that I think almost every one of 

 the thousands of shells brought home, except some of those of very small size, such as 

 young, etc., really passed once if not oftener, under observation. 



In my opinion, this method, in such cases as that at Steinheim, is far superior to the 

 ordinary one of examining formations and collecting therefrom such specimens as strike 

 the eye. Such collecting is largely governed by the preconceived ideas of the collector 

 and he cannot, however honest, avoid seeing by preference, and involuntarily selecting the 

 things which are forecast in his own mind. There is also great danger that he will be 

 content with any evidence which fills ovit his ideal, and stop short of the discovery of the 

 exceptions, which, though few in number, are essential to the verification of his logical 

 conceptions. 



Illustrious examples in all fields of science are involuntary witnesses to the truth of 

 these remarks, and show also, that even repeated observation and mechanical means 

 cannot always correct the personal equation or eliminate the errors arising from this 

 source. My effort has been to use such clumsy mechanical means as the present 

 state of zoological science permits, and of the success of these, others must be the judges ; 

 in this case the writer can only appear appropriately as an advocate. 



My studies led me to think either that Dr. Hilgendorf had made the most serious 

 mistakes with respect to the stratigraphical position of the forms, or that I had collected 

 them without sufficient care. Determined to leave as little risk of error as possible, in 

 this respect, I again visited Steinheim early in the following spring, as soon as the snow 

 began to leave the ground. Though this time, as before, almost continually suffering from 

 adverse weather, I succeeded in collecting largely. The old hole was reopened in the Old 

 Pit, widened, and specimens again cohectcd. Another hole to the northward, but within 

 the limits of the pit, was sunk to the Jura clay. A hole was also dug in the Little Pit, but 

 not so successfully, owing to the rainy weather, which rendered the work of undermining 

 the sand dangerous. In the East Pit, although a more persistent attempt was made in 

 two places, the abundance of water rendered it too difficult to go beyond the limits 

 shown in the section. The Cloister Pit was dry, but here I did not deem it necessary to 

 go deeper than was essential for the development of the upper series of formations. The 

 most exact measurements were made upon the face of every stratum, and quite a 

 number of sketches showing the position and character of the limestone partings and 

 sandbeds. In fact, every possible precaution was taken to insure accuracy, so far as 

 the work went.^ The plotting of the sections consisted of the reduction of the 

 measurements to one one-hundredth part of those actually taken, and are approximately 

 correct as shown in the table of the Geological Sections. 



As remarks have been published which show that some importance is attached to the 

 length of time actually spent by me at Steinheim, it becomes necessary to state, that it 

 was about five weeks in all : once two weeks, and at another visit three weeks. Where 

 such earnest controversy exists, as that to which the Steinheim shells have given rise, 



^No colleetiniis were made from the limestone partings for transportation. auJ I found by careful examination of 

 durinfr the second visit, except where these contained addi- each limestone layer, that no additional information was 

 tional forms. Such a collection would have been too bulky obtainable, except in isolated instances. 



