354 bulletin: museum of comparative zoology. 



CONCLUSIONS. 



1. The coral reefs exercised a controlling influence in the develop- 

 ment of Gotland lithology and stratigraphy. 



2. Little reliance can be placed on coral reef faunas in correlation, 

 since species of different horizons are apt to occur in association. 



3. The fauna of any basin about a coral reef is apt to exhibit many 

 differences when compared with the fauna of another basin. 



4. Discordances of strata are readily developed in sedimentation 

 about coral reefs-and have little or no significance. 



5. Conglomerates and worn shells should be present in deposits 

 about coral reefs, and neither indicates a transgressing sea nor a land 

 interval. 



6. Directional and quantitative variations of inclination of strata 

 have wide limits about coral reefs, and should always be considered 

 in coral reef stratigraphy. 



7. In general, the rock of any reef is older than that lying at the 

 same level on its flanks. 



8. Strata of the same time interval will lie at dift'erent elevations in 

 the different channels between the reefs. 



9. The ultimate solution of the problems of Gotland stratigraphy 

 will probably be reached by a study of the relations of the sediments 

 and the faunas to the coral reefs. 



