74 THE NAUTILUS. 
Ohio River drainage. Between the Scioto and the Hocking 
Rivers is a fairly large stream known as Raccoon Creek. It is 
now polluted with mine waste and at the time of my visit to it 
three or four years ago I found no living mollusks in the creek, 
and only one or two dead Unios. 
East of the Muskingum system is the Mahoning River and 
Beaver Creek, crossing the Ohio border into Pennsylvania. I 
know nothing of the Goniobases of these streams, but suspect 
that if any occur in them it is G, pennsylvanica Pilsbry, the 
Goniobasis of the upper Ohio rivers. 
The chart of this distribution shows that livescens crosses the 
northern section of Ohio in the drainage of the Great Lakes and 
down two streams of the Ohio River drainage. Semicarinata 
occupies the three largest streams of the Ohio River drainage 
from the Scioto at about the center to the Great Miami, dis- 
charging at the southwest corner of the state. 
If we grant that the same laws which have governed the re- 
peopling of Lake Erie with Naiades have controlled in the case 
of livescens, this species entered the Maumee River through the 
Wabash, spread eastward to the Niagara and beyond. It man- 
aged—by means which the geologists might explain—to cross 
the divide between the Cuyahoga and Tuscarawas River, possi- 
bly thence into the Hocking. 
Other species of Goniobasis than those micntonen have been 
recognized as occurring in Ohio, and other local races may yet 
be described, but I feel certain they can all only prove to be 
descendants of the two parent stocks, livescens and semicarinata. 
SOME LARGE SPECIMENS OF ARGONAUTA. 
BY CHARLES W. JOHNSON. 
The largest species, or the largest example of a species, is 
always a subject of special interest, both to the biologist and 
the collector. Individual variation is not fully understood and 
cannot always be attributed to favorable or unfavorable environ- 
ment, or the abundance or lack of nutrition. Individual varia- 
tion has often led to arguments among conchologists as to 
