R. Pumpelly on the Delta-plain of the Yellow River. 219 
If inorganic, these forms may, of course, be looked for in 
other formations, wherever the same conditions have existed. 
Prof. Newberry, ‘of Columbia College, recently informed the 
writer that he once observed a somewhat similar structure in 
altered Tertiary rocks in Oregon. Nothing of the kind, how- 
ea Sa the Paleotrochis, appears to have been hitherto 
escribed 
New Haven, Ct., Jan. 25, 1868. 
a 
Art. XX V.—On the Delta-Plain, and the Historical Changes 
in the course of the Yellow River; by RarHaEL PumpEnty.} 
Tue extent of the great plain of Eastern China is pretty 
well known from native and Jesuit authorities. It lies ina 
ig 
south, ss west of Jiining “ii (onan, and then t turning 
east i i wang (chau) and a. of 
* Am. & Asnocidiioa of Science, Burlington Meeting, August, 18 
t eological Researches in aoe Mongolia and Japan, pantie the Mewid 
pode: ‘1863, 7 ee pee: Smithsonian Contributions to 
Knowledge, No. 
