410 
factors clearly influencing—more particularly, of course, in the channel— 
both the depth and softness of the bottom deposits (regarded as a 
medium or as a substratum for the bottom population), and also the food 
supply of the bottom animals so far as it is brought to them by sedi- 
mentation. In the two richer reaches of river above Havana the average 
flood velocity in recent years (around 0.9-miles per hour) has been only 
about 3% of that between Havana and Lagrange (1.5 miles per hour), 
and less than half the average between Lagrange and Grafton (1.9 
miles per hour). 
Though there is usually, both in the slower and swifter reaches of 
the river, if we except the cases of some sharp bends, some retardation 
of current between mid-channel and shore, with accompanying increase 
in sedimentation and noticeable differences in the composition of the bot- 
tom populations, these differences in the less rapid sections above Havana 
are neither very important quantitatively nor correlated so far as can be 
seen. The average poundages per acre of bottom animals between Chilli- 
cothe and Copperas Creek dam in the channel and the shore zones (chan- 
nel, 239 lbs.; 4—7-foot zone, 372 lbs.; 1—3-foot zone, 225 lbs.) are in 
fact so nearly the same that little if any significance can be attached to 
the differences; while in the 16.8 miles between Copperas Creek and 
Havana (channel, 3,029 lbs.; 4—7-foot zone, 1,960 Ibs.; 1—3-foot zone, 
920 lbs.) the differences in weight between theshore and channel stocks 
are in the reverse of the direction that might be expected. There is, 
however, a decidedly sharper contrast below Havana between the physical 
characters of the channel and shore zones, and in and to either side of 
the stretch of comparatively hard-bottomed channel between Havana and 
Lagrange a corresponding contrast in the richness of the bottom fauna 
that is without much question connected with it. In this section of 42.5 
miles the 4—7-foot zone (282 lbs. per acre) had stocks thirteen times as 
rich as those of the channel (22 lbs.) ; and there was a further large in- 
crease shown in the stocks in the 1—3-foot zone. 
Certain special influences that may affect the bottom-fauna yields 
in the river below the Lagrange dam are discussed in a following sec- 
tion. ; 
2. ALL-ZONE AVERAGES AND TOTAL STOCKS 
All-zone averages of the bottom-fauna stocks of the four main river 
reaches below Chillicothe based upon rough acreage-weightings show a 
figure for the first 43.7 miles below Chillicothe (264 Ibs. per acre) about 
the same as the average for the entire 180.5 miles between Chillicothe 
and Grafton (261 lbs.) ; for the 16.8 miles between Copperas Creek dam 
and Havana about ten times that (2,693 Ibs.) ; for the 42.5 miles be- 
tween Havana and Lagrange a rate of yield (88 lbs. per acre) about 
one third of the general river average and about one thirtieth of the rate 
in the richest section; and for the 77.5 miles below Lagrange (10.4 lbs. 
per acre) less than one twenty-fifth of the 180 mile average and less 
