W. E. Ford — Interesting Beryl Crystals. 223 



urements due to the vicinal character of the faces, exact sym- 

 bols cannot be assigned to these forms. In some places the 

 pits form a single line down the length of the crystal, not 

 encroaching at ail on the faces of the dihexagonal prism at the 

 sides, as shown in figure 9. More generally they are in two 

 or more parallel and adjacent lines and interlock with each 

 other in a very complicated manner, as shown in figure 10. 

 The pits average 2 mtn by l*5 mm in size. The crystals show a 

 tendency to taper at the ends on account of the etching and 

 rounding of the prism faces. 



Acknowledgment should be made of the courtesy of Mr. 

 Ernest Schernikow of New York and of Messrs. H. C. Bum- 

 pus and L. P. Gratacap of the American Museum of Natural 

 History in New York, for furnishing for study the crystals 

 illustrated in figures 1 to 4. The writer also gratefully 

 acknowledges the frequent help, through criticism and sugges- 

 tion, of Prof. S. L. Penfield during the preparation of this 

 article. 



Mineralogical Laboratory of the Sheffield Scientific School 



of Yale University, New Haven, Conn., June, 1906. 



