46 HYATT ON THE TERTIARY SPECIES 



layer of clayey sand. The lowest of these consisted of true Steinheimetisis shells, 

 and the upper of steiMm^^i^ shells. In this statement, then, we see that Dr. Hilgendorf 

 did not find two distinct deposits, but one deposit with two distinct layers of shell. 

 Unfortunately, the conditions of the problem demand that there should be a wider 

 separation than this, or else there comes in the doubt that in this case, at any rate, 

 there may have been the overlapping of local and contemporaneous colonies, so common 

 in these deposits. This same section also assures me that in my sections in the Old Pit, 

 the bottom of the deposits at that place was reached. I carefully kept separate ^ until 

 after I had drawn and studied them, the samples of fossils gathered from pockets 

 in the Jura clay itself, and these contained specimens of the PL multiformis, which 

 were not only important in respect to being found in this position, but still more 

 so from the fact that they were transported shells. This was the conclusion arrived 

 at by comparing them with other specimens. They were encrusted with brown 

 limestone, and otherwise roughened like rolled shells. They imply that PI. m,ultiform,is 

 existed before this lowest layer was deposited, and that the few specimens found were 

 transported from some other locality where living sj)ecimens existed, and had been 

 in the water long enough after the death of the mollusks to acquire their rolled 

 aspect, and encrusted outer surface. 



I farther assured myself from the owner of the pit before digging the hole, that 

 the floor of the pit had not been disturbed since Dr. Hilgendorf's visit, and dug 

 near the spot pointed out to me as the one where he had sunk a pit. This, however, 

 proved to be a mistake, since the limestone was unbroken, and Dr. Hilgendorf 

 claims that the section No. 6, of my digging, was nearer the hill, and not so deep as 

 those explored by him, except his No. 4, and that I struck the Jura clay at a much 

 less depth, so that in place of Nos. 1-2, I found only his bed 5, equivalent to his disco- 

 ideus zone. 



He states that the fish remaina occurred in his zones 6 and 7, while they occurred 

 much lower in my sections — namely in bed c. His zones 6 and 7, however, are the 

 equivalents of k. I. in my sections, and the whole thickness of my sections were between 

 40 and 55 feet in the Old and New Pits. This is a very significant fact, since he states 

 that the total thickness of all the strata were 45 Wurtemburg feet — about 42 Eng- 

 lish feet. "Diegesammte Machtigkeit der l)cobachteten Schifchten wiirde sich auf etwa 

 45 Fuss belaufen, wenn dieselben der namlichen Stelle sammtlich in gunstiger weise entr 

 wickelt waren." 



The number of zones which could be distinguished petrologically was, as stated by him, 

 about 40 in all ; but this 1 could not use for comparison, the nimiber of layers differing so 

 greatly, that no reliable compai-ison could be made. The total thickness, also, must have 

 been considerably lessened in the Old Pit at the time of Dr. Hilgendorf's visits, since he 

 did not find the oxi/stomns and suj)remus zones ht're, but in the Cloister Pit, whereas, 

 these were well shown in the New Pit immediately adjoining the Old Pit, at the time of 

 my explorations. 



1 It is of course understood in all these cases, tliat no exposed surface, or without digging under the limestone 



pains were spared to make every samplo p„.-xeotIy reliable, layers, etc. No one but a tyro would think of neglecting 



and that in no case was a hole sunk except through such precautions, 

 unbroken limestone, nor was anything gathered from an 



