AN INTERESTING TSKUDOSOLID 299 



On the whole, therefore, this pseiidosolid is an extremely 

 suggestive material and deserves the study which we hope in 

 future to give it. 



We take pleasure in acknowledging the very efficient assist- 

 ance which has been afforded us both in the experimental work 

 and in the computation by our associate, Mr. C. E. Van Orst- 

 rand ; also our obligation to Mr. Norman W. Carkhuff for 

 placing the facilities of the photographic laboratory of the 

 Geological Survey at our disposal. 



