395 



SECTION. 

 OF EISENSTEIN. MIDDLE LIAS. 



LlEBENBUKG. 



As to the description of this example, the Author observes, 

 that in No 2, the grey blue clay, he finds only the Am. 

 Spinatus in the upper half of the beds, and Am. Margaritahis 

 in the lower half; and both species are abundant. He also 

 remarks that he can engage with certainty that Am. Spinatiis 

 first occurs at 9 metres distance above the bottom line of the 

 clay marked No. 2 division. In the 18 metres of greyish blue 

 clay which seem to be homogenous throughout, although no 

 exact medial line can be drawn, yet the phenomenon of one 

 species of Ammonite being replaced by another species, is of 

 striking interest biologically, as illustrating the law of restriction 

 of their short range of life. In the lower moiety of No. 2, 

 greyish blue clay, U. Schlonbach also notes that the fauna of 



