454 INFERIOR OOLITE AMMONITES. 



which they are found are subjacent to beds containing " coronate" Ammonites. 

 In other words, in South America there is the same geological sequence as in this 

 country, namely, beds with Coronati overlying beds containing Sonninise, Am. 

 Sauzei, &c. 



This correspondence of the faunal sequence in Europe and South America 

 seems to be worthy of attention. In connection herewith it may not be amiss to 

 notice certain ideas of Dr. Johannes Walther in ' Einleitung in die Geologie als 

 historische Wissenschaft,' vol. ii. I have, unfortunately, not seen the original 

 work, and can only submit the following remarks on an abstract which appeared 

 in ' Natural Science,' vol. iv, No. 26, p. 245. Dr. Walther points out that, in 

 possessing a chambered shell, Ammonites are comparable to Nautilus and Spirula, 

 " which both live at the bottom of the sea, and are very restricted in their 

 distribution ; yet their dead shells are found over an enormous area. ... In 

 the mangrove swamps of Java, on the sandy shores of Ramesveram, among the 

 volcanic ashes of the Canaries, and on the coral reefs of the tropical zone, 

 everywhere are the shells of Spirula found scattered. No coastal deposit in the 

 whole Indo-Pacific province is free from Nautilus.'''' 



At first sight a similar distribution of Ammonite-shells after death would 

 readily explain the correspondence in the faunal sequence in Europe and South 

 America; but only if it be assumed at the same time that Ammonites were 

 pelagic and not littoral forms. If, however, the faunal sequence did depend on 

 distribution of Ammonite-shells, it would make these fossils of even greater 

 importance for purposes of precise zonal correlation, and it would still further 

 weaken the sudden-entombment idea of Morris and Lycett alluded to in p. 446 ; 

 the beds of closely packed Ammonites to which they allude might be assumed to 

 result from the bringing together during long periods of time of a large number 

 of shells at certain places where there was a proportionately very small amount 

 of sediment to cover them. 



However, it may not be unreasonable to make the following remarks on the 

 dispersal idea. Even if a large muster of Ammonite- shells were removed away 

 from the place where they lived, it may be assumed that at the same time a far 

 greater number may have been left behind to be buried on the spot. Dispersal, 

 again, would expose the shells to many vicissitudes, especially when they came into 

 shallow water, or when they were landed on the shore. Now in many Ammonites 

 the appendages of the mouth-border are exceedingly delicate, more delicate 

 than the shells of Nautilus or Spirula, because they project with very thin sup- 

 porting stems from the edges of the aperture. Such appendages would be very 

 liable to be broken off; and they would be damaged much more easily than the 

 rounded aperture of Nautilus. Ammonites themselves would be differently liable 

 to damage, even those closely related ; thus the same accident which would break 



