412 Bodge and Beecher — Occurrence of Upper 



space of two degrees. The pyramid v (301) was very bright 

 and quite large and well defined; and the pyramid e (101) 

 was also bright but very small. The basal planes were 

 rounded and apparently pitted and rough. 



On account of the very minute character of the pyramidal 

 planes, correct measurements were difficult to make, the use of 

 the signal in a reflecting goniometer being entirely out of the 

 question, on account of the small amount of light and reflec- 

 tion in the goniometer being all that could be employed. The 

 manipulations necessary to place the crystal in position were 

 also very delicate. The angle between 301 and 301 gave the 

 best definition, and the mean of many measurements, 127° 32\ 

 gives the axial ratio 



a:c=\ : 0-67643 



The following are calculated and measured angles for the forms 

 301 and 101 . 



Calculated. Measured. 



301 ^ 301 *127° 32' 127° 32' 

 301 -. 100 26 14 24 30 



301 x. 101 29 41 28*" 28 1 

 101 ^ 100 55 55 28" 54 39 30" 



101 ^ 001 34 4 32" 35 20 30 



Putile gives the axial ratio a : c=l : 064415, and though the 

 habit of these crystals differs from that of the other members of 

 the group, in that the diametral prism is alone present, it is to 

 be noted that the pyramid v (301) here prominent is a twin- 

 ning plane with rutile. 



TJ. S. National Museum, Feb. 29th, 1892. 



Aet. LI. — On the occurrence of Upper Silurian Strata 

 near Penobscot Bay, Maine ; by William W. Dodge and 

 Chaeles E. Beechee. (With map.) 



On the island of North, Haven in Penobscot Bay, there is 

 an extensive exposure of abundantly fossiliferous rocks of 

 Silurian age. 



The region where they are found is included in United 

 States Coast Survey chart 311a (1 : 20,000), Fox Islands 

 Thoroughfare, also in 310(1:40,000), West Penobscot Bay. 

 The sketch map, herewith, indicates the points at which the 

 fossils specified by Mr. Beecher in the second part of this paper 

 were obtained, giving also strike, dip, and character of beds. 



For five-eighths of a mile northward from Fox Islands 

 Thoroughfare (the strait which separates North Haven from 



