28 Forbes — Epidote from Huntington, Mass., and the 



Nos. 1, 2 and 3 may be grouped together as the lowest of 

 the three zones, which shows a commingling of fossils that 

 elsewhere occur in the lowest Washita and in the Fredericks- 

 burg, with a few that range down into the Trinity division. 



In north Texas the same species of Ammonites occur in the 

 Kiamitia and Duck Creek (the Preston beds) at the base of the 

 Washita and in the Good land limestone, which belongs in the 

 Fredericksburg. Gryphcea fornioulata is a Kiamitia species. 

 Exogyra texana is most abundant in the lower part of the 

 Fredericksburg, though it ranges beyond both the lower and 

 the upper limits of that division. The Echinoids also occur 

 in both the Fredericksburg and the Washita. Requienia 

 texana, Pleuromya hnowltoni and Tylostoma pedernalis are 

 other forms that suggest a lower horizon than the Washita. 



The evidence of the fossils taken altogether is in favor of 

 the view that a part of the Fredericksburg is represented here 

 and that it grades into the basal Washita so imperceptibly that 

 no palaeontologic line can here be drawn between them. The 

 Caprina limestone and its characteristic fauna, which in Central 

 Texas, south of the Brazos river, usually affords such a distinct 

 plane of separation, is absent here, as it is in north Texas and 

 in all the outlying Lower Cretaceous areas of Kansas, Okla- 

 homa and New Mexico.* 



Akt. YI. — On the Epidote from Huntington, Mass., and 

 the Optical Properties of Epidote • by E. H. Forbes. 



In the fall of 1892, Mr. W. L. Angell of Huntington, 

 Mass., brought several crystals to the Mineralogical Laboratory 

 of the Sheffield Scientific School for determination. They 

 resembled zoisite in color and general appearance, but upon 

 examination proved to be epidote. Their light color and the 

 absence of the usual green of epidote indicated a low iron 

 percentage and suggested a chemical and optical investigation. 



Abundant material was furnished by Mr. Angell, upon whose 

 farm the mineral occurs, and some was also collected by Profs. 

 S. L. Pentield and L. Y. Pirsson, who visited the locality and 

 found the epidote occurring in a seam in gneiss associated with 

 quartz, biotite, albite and calcite. When the crystals project 

 into cavities, they have a dark gray color and are clear and 

 transparent, but when imbedded in the matrix they are much 

 lighter in tone and less transparent, due undoubtedly to crush- 

 ing, as the crystals are permeated by cracks and some are bent. 



*See this Journal, September, 1895, p. 234. 



