Great Canyon of Ifnclso)i River. — Speneer. 293 
the lofl, the ininu'diatc iiosilion is open to sonic variation of 
location. 'l"o nearly 9,000 feet, its maxinnini hrcadtli i^ 
defined, and thus we have the pr(X)f of the valley c".::- 
tinuini^' to a point 71 miles from the liead of the ranyon, 
which is ahout 100 miles from Sandy Hook. The edge of 
the continental shelf is taken at a depth of 500 feer, inside of 
which the gorge has receded nearly 30 miles. The floor of 
the channel and gorge is covered witii blue cla}', while the 
level shelf is covered with sand. 
I am now able to analyse this feature e(|ually well with the 
canyons of the Congo and Cai)e Wrdc. or the .Vntillean re- 
gion, with the advantage of having more knowledge of the 
adjacent topographv and geology, so that its date can be de- 
termined as pertaining to the early Pleistocene period, and 
that there seems no other feasible explanation of its origin 
than that it was formed as a land valley when the region was 
9,000 feet higher than now. For some reasons one might be 
inclined to reduce this amount by 2,000 feet on account of 
epeirogcnic depression of the continental slope, but this is re- 
futed by outside information. 
The study of the shallow channels on the continental shelf, 
shows, after a subsidence following the period of elevation, an- 
other small elevation of 250 feet, obtained in age post-Columbia. 
Subseciuent sinkings and minor changes are also noted. 
MIOCENE BARNACLES FROM GAY HEAD, MASS.. 
WITH NOTES ON BALANUS PROTEUS, 
CONRAD. 
By JosKPH A. CUSHMAN. Boston. Mass. 
During the last two summers two collecting trips to Gay 
Head, Alarthas \'ineyard. were made by the writer, one in 
July, 1903, the other in August, 1904. At both times a con- 
siderable number of specimens of the fossil crab. Areluieo/^la.v 
signifera Stimpson, were collected, in all. several hundred 
specimens. Among these were a number showing the carapace 
almost completely. Ujxju examining several of these, peculiar 
circles were noted on the shell. The counterparts revealed the 
bases of barnacles, the upper parts of which \ierc imbedded in 
