1889. ] NEW YORK ACADEMY OF SCIENCES, 117 
The following paper was read by title: 
A NEW GENUS OF TERMITOPHILOUS STAPHYLINIDA, 
by Tuomas L. Casey. 
In this article, published in the ANNALS, Vol. IV., pp. 384— 
387, CAPTAIN CASEY describes, under the name of Termito- 
gaster insolens, a very curious staphylinide form found in the 
‘nests of certain species of white ants on the Isthmus of Panama, 
and brought by Mr. Dudley. 
It is defended against injury from the Termites among which 
it dwells, apparently by ‘‘ protective mimicry,” its elytra being 
short and inconspicuous, while its abdomen is rather distended, 
white, and soft,—the whole insect bearing a-strong general 
resemblance to a white ant. 
The paper announced for the evening was then read’ by Mr. 
WiuuiamM L. EvseFrer, C.E., as follows: 
ON THE TENDENCY TO CONTAMINATION IN ARTIFICIAL PONDS, 
IRRESPECTIVE OF VOLUME; WITH APPLICATION TO THE 
QUAKER BRIDGE DAM. 
There are three conditions to be considered, namely: (1) 
stagnant water in artificial ponds; (2) contamination originating 
from stagnant water; (3) impurities carried into the pond from 
above and settling upon the bed, and thus becoming a source of 
contamination. 
There can be a current through a pond not necessarily com- 
mingling with the entire body of the pond. The standing 
water or undischarged volume of a pond will be of different den- 
sity and quality from the limpid inflow running over a rocky 
and gravelly bed. 
Where the outflow is limited, —the outflow being always greatly 
less than the volume of the pond,—the current through the pond 
cannot have sufficient volume to mingle these waters of different 
condition and density ;—the cohesion of the current volume being 
stronger than its adhesion. 
Water will flow between walls of water, as the Gulf Stream 
through the Atlantic, and as the Hudson River on change of 
tide (the flow in mid-river continuing for some time up or down 
stream as the case may be, while on both sides the flow is in an 
opposite direction), or asa small stream discharging into the 
