96 Smith — The Occurrence of Coral Reefs, etc. 



zon, and contains the fauna of the classic Zlambach beds of 

 the Fischerwiese in the Tyrolian Alps, that is of the Noric 

 horizon of the Upper Triassic. 



The group of Astraeidae is abundant in all these localities, 

 except in the Blue Mountains, and since they are still impor- 

 tant reef-builders, and now confined to the hottest parts of the 

 tropics, where the temperature does not fall below 74° F., it is 

 reasonable to suppose that in Triassic time they lived under 

 approximately the same conditions. This makes it probable, 

 if not certain, that the sea had a tropical temperature up to 

 60° 1ST. Lat., at least in the Pacific Ocean. 



Speculations as to ancient temperatures of the sea are inter- 

 esting, but of much more importance to geologists is the fact 

 that this Noric coral fauna gives us a new and distinct bench- 

 mark, which in its marked characters and wide distribution 

 equals that of the zone of Tropites subhullatus, and enables 

 the positive correlation of strata that heretofore have been a 

 puzzle to stratigraphers. 



Stanford University, California. 



