74 11. F. Brid — Studies of Muir Glacier. 



The other three of Mr Cushing's diahase specimens are quite 

 typical rejiresentatives of this rock, altliough tliey are all con- 

 siderably altered. They differ mostly in the coarseness of their 

 structure. One contains a little basaltic hornblende and one is 

 slightl}' am3'-gdaloidal. 



Petrographical Laboratory, 



,Toiix8 Hopkins University, Ajiril, 1891. 



