198 Evolution and Distribution of Fishes 



downwards into the shallow waters of the now elevated 

 lagoon along with discharges of gases at each climax of 

 oscillation caused asphixiation of the marine organisms. 



So, if we make use of the exact statistics gathered by 

 Bonney, Judd, and specially by I. C. Russell ( // : 284-296) , 

 the entire deposit may have been made within a few days. 

 Or at most three or four main periods of activity, such as 

 Walther's photographs of the strata suggest, may have 

 occurred, each within a few weeks or possibly longer periods 

 of time apart, and each depositing four to twenty feet of 

 volcanic lime-dust produced from pulverized coral-rock. 

 The mention by Walther of four successive medusoid zones 

 (p. 210 of his work), and of several zones with abundant 

 Leptolepis fish remains favors such a view. 



The revelation given by these Solenhofen beds of a rich 

 fish-life is probably unequalled by any other single rock 

 formation, if we except the even richer Monte Bolca de- 

 posits. Whole shoals of individuals belonging to the genus 

 Leptolepis must have perished in some freshwater area, and 

 been swept rapidly on as dead bodies where they became 

 spread out and entombed in sidewise manner. Some fishes 

 — probably by action of poisonous gases — had time to 

 disgorge their food before death; while others show small 

 fishes still in the alimentary canal, as with Caturus and 

 Thrissops, whose food seems largely tp have been the small 

 fry of Leptolepis. 



As indicating the extreme richness of the fish-fauna thus 

 brought together we subjoin Walther's list in its entirety. 

 And as his combined results were gathered from various 

 localities along the Wiesenthal, each locality is indicated 

 by a capital letter that is the initial for the locality name. 

 These are Kelheim (K), Eichstadt (E), Solenhofen (S), 

 Mornsheim (M), Langenaltheim (L), Daiting (D) and 

 Nusplingen (N). 



Elasmobranchii. Fain. Cestraciontidae. 



Order Sqnalidae. f-m Acrodus falcifer, E. S. L. 



Fam. Notidanidae Fam. Scyllidae. 



m Notidanus eximius. m Palaeoscyilium formosum 



E. D. N. E. S. 



m Notidanus intermedins M. m Pristiurus eximius E. 



m Notidanus serratus N. Fam. Lamnidae. 



m Notidanus ^.cagneri S. m Sphenodus nitidus S. 



