BULLETIN OF THE UNITED STATES FISH COMMISSION. 287 
aquarium 5 the aquaria being constructed on the margin of the pond or 
reservoir used, as shown in the accompanying illustration, Plate 1 5 the 
idea being to have a water-pen or pond-garden (A) extending back from 
each aquarium front, and to be surrounded by a wire or other fence or par- 
tition (B)of sufficiently small mesh to prevent the escape of the occupants, 
but large enough to allow the smaller fry, which would furnish them with 
food, to pass through freely. (C) represents the glass fronts. (D) the 
upper or perforated aquarium bottom, which allows the escape to a 
lower funnel-shaped bottom (E) of all sedimentary deposits. (F) rep- 
resents rocky eminences containing pockets, in which could be planted 
aquatic vegetation at depths adapted to their needs. The whole creat- 
ing a close approximation of natural conditions. An arrangement of 
wire gates would keep fishes in close confinement for short periods for 
observation, or would keep some, while others were allowed to roam at 
will in their domain. 
Plate II represents a cross-section of the same, showing building over 
the aquaria, and greenhouse roof to pond-gardens. 
The advantages of some such plan will, I think, be apparent to all 
who have experience on the subject at least. It is simply imitating 
nature more closely and getting rid of artificialities. 
The conditions would afford natural vegetation, sunlight, mud, sand, 
and rocks, with abundance of room in which to move about freely and 
seek for natural food. 
By such a plan also the necessity for circulatory apparatus is dis- 
pensed with, the circulation caused by the movements of the fishes, 
changes of temperature and evaporation, together with the aeration or 
oxygenation effected by the plant life being ample as in the pond. 
It might be argued that, with so large a space, fishes would keep 
hidden from view. The experience of the writer has been that when 
the fear of danger is removed and animals become confident of an abil- 
ity to escape at will when threatened by danger they lose their timidity 
and become both bold and curious, and are more easily and satisfactor- 
ily viewed than when under the influence of fear in close confinement. 
The deer, the most timid of animals, when confident of safety, becomes 
perfectly content, and without desire to escape except to seek its kind 
for company. 
The experience of the writer in the care of fishes and reptiles and 
other animals as well, is to the same effect. 
