254 The American Geologist. October, 1895 
It will be seen that the term area can be used equally well whether 
the shell is equivalvular or inequivalvular. When shells of the first kind 
are under cf)nsideration it is not necessary to speak of the right side 
of an area; but in the latter of course it becomes important to describe 
both valves minutely, and then the terms right and left areas can be used 
and their different relations accurately noted. 
In applying these terms to shells with anterior hinges and having 
wings some modifications are necessary. In a Pecten or Avicula, for 
instance, the oral area is the ventral wing, and it would be perhaps bet- 
ter to continue to use the term wing. The jjedal sinus is the byssal 
notch, and there is no reason why this term should not also be contin- 
ued in use, if it is understood that the areas are homologous and these 
terms synonymous. The branchial area in these shells is distinguish- 
able from the siphonal in a number of forms, as has been pointed out to 
the writer by Dr. Jackson. 
A good example of the results likely to follow from the application of 
this or any natural system is found in my cursory study of Malleus. 
Taking up this shell simply to see whether this terminology would ap- 
ply, I discovered that the so-called wings are not true wings. The true 
wings of the oral area are arrested in growth at the end of the neanic 
(adolescent) stage. In the first of the ephebic (adult) substages the 
ventral margins of the pedal area in both valves become hypertrophic 
and' grow out into the long so-called anterior wings. The bands of 
growth may be followed in any shell, sufficiently well preserved to show 
the true wings in the young, as they pass around the byssal notch and 
extend ventrad to build up the great ventral arms that are really spatu- 
late outgrowths of the ventral margins of the pedal area. 
The Equatorial Counter Currents. W. M. Davis, Cambridge, Mass. 
(Read by title.) 
IntereHting Features in the Surface Geologij of the Genesee Region. 
H. L. Fairchild, Rochester, N. Y. This was a lecture illustrated with 
lantern slides, chiefly relating to the Pinnacle hills in the southeast 
edge of the city of Rochester, which were described and their mode of 
formation discussed by this author in the last July number of the Am. 
Geologist (vol. xvi, pp. 39.51, with map). 
JajMti. Gardner G. Hubbard, Washington, D. C. (Read by title.) 
Great Falls of the Mohau-k at Colioes, N. Y. W. H. C. Pynchon, 
Hartford, Conn. This paper was illustrated by lantern views. The Co- 
hoes falls have been worn back about seven-eighths of a mile since the 
end of the Ice age, in Hudson River slates which dip with a slight in- 
clination down stream. Clear indications of a drift-filled preglacial 
channel are found starting from the Mohawk river about two miles above 
■the falls, passing eastward on the north side of the river and opening 
•out with a broad mouth into the Hudson valley at Waterford. 
Section E held a joint session with Section H (Anthropol- 
ogy) on Tuesday afternoon, in which the following paper was 
presented : 
