1881 .] 
277 
[Wadsworth. 
Dr. Hunt separated the modified granite from the unmodified 
granite by making them distinct rocks and of diverse origin. 
(Proc. Bost. Soc. Nat. Hist., 1870, XIV, 47 ; 1875, XVII, 508-570). 
The question of the dip of the argillite in the Paradoxides 
quarry is an interesting one, in regard to which various views 
have been held. 
In 1856 Prof. Wm. B. Rogers, in the first announcement of the 
discovery of fossils here, stated that “ the dip in the quarry ” was 
“X. 20° W. at an angle of about 45 degrees.” He also described 
the granite adjacent as “ granitoid and sienitic masses” which he 
held to be igneous. (Proc. Bost. Soc. Nat. Hist., 1856, VI, 27-80). 
Dr. Chas. T. Jackson held that from its grain and cleavages 
the argillite dipped north 50°, and regarded the syenite as eruptive 
(1. c., p. 42-44). 
Mr. Isaac Lea stated that the dip was south 68°. His determin- 
ation of the dip was based on the presence of the fossils, and their 
dip (Proc. Phila. Acad. Nat. Sci., 1857, IX, 205). Professor Shaler 
in his paper above referred to makes the dip to the northward. 
Mr. W. O. Crosby, basing his conclusions on tho trilobite remains, 
states that the rock dips to the south at an angle of from 80° to 
85° (Contributions p. 152), while the rock adjacent is recognized 
as a granite. 
My observations, based on the fossil remains, made the dip 
south or a little west of south at an angle of 55°, thus agreeing 
nearer with Mr. Lea than with Mr. Crosby. The discrepancy is 
probably owing to the angle of inclination varying in different 
parts of the quarry. It seems, however, probable that Mr. Lea 
would have had superior advantages for determining the position 
of the fossils at the time he visited the quarry than either Mr. 
Crosby or myself ; that is, he would be able to draw his conclu- 
sions from a far greater number of specimens. It appears, then, 
probable that his determination of the dip is the most likely to 
be correct. It is probable, judging from their writings, that Pro- 
fessors Rogers and Shaler based their conclusion regarding the dip 
of the argillite upon its structural characters. 
