BULLETIN OF THE UNITED STATES FISH COMMISSION. 5 
Indian Ocean 5 and although the capacity of such simple vessels is 
necessarily small, it has sufficed for the successful importation of several 
young sturgeons from Hamburg to Liverpool.” 
j The special advantages of the Mortimer ship-aquarium, for purposes 
like the present, are as follows: 
( 1 ) Its extreme simplicity, and the small amount of trouble involved. 
(2) Its handiness in conveyance to and from the ship, as well as on 
board. 
(3) Its transparency, giving every facility for observation, whether 
for study or mere inspection as to purity of water and health of fish. 
(4) Its easy swinging motion when suspended, the surface of the water 
being but little disturbed during considerable departure from the ver- 
tical center. 
(5) Its facilities for feeding the fish if required, and for the removal 
of refuse, as also for drawing off the water when requisite, and supply- 
ing clean water in its place. 
( 6 ) Its facilities for simple aeration. 
(7) Its saving, more than any other form of vessel, of the fish from 
injuring themselves by striking against the prison walls, by the motion 
of the ship or otherwise, a matter of the greatest importance. 
( 8 ) Its comparative strength, similar aquaria having been carried 
four times across the Atlantic in all weathers, and in the long voyages 
of a sailing ship, without coming to grief. 
(9) It facilitates also the use of sand as a bed or bottom.* 
The soles, by the waving motion of their body and fins, cause the 
sand to rise, and, in falling, to cover them so effectually that they are 
scarcely discernible, as evidenced above. Sometimes only their eyes, 
or an outline of the head or body, can be seen; at others a circular 
track only is visible, caused by the continued moving of the fish, which 
perforce results in a circular outline of its track. The comfortable 
look of the soles, often to be seen in our large aquaria, was so striking 
in those put into the globes for Mr. Duncan that it made me more than 
ever bent upon so accommodating them. They had all the appearance 
of being literally tucked up in their bed, and lightly breathing. 
These advantages are difficult or impossible of attainment, singly or 
in combination, in vessels of wood or iron. Much ingenuity has been 
exercised as to the construction and aeration of tanks of various kinds 
and sizes and the regulation of temperature for transporting soles on 
a far larger scale, but the results hitherto have not been commensurate 
with the labor expended, and the importation of soles to America in 
greater numbers than above recorded has yet to be accomplished. 
There is, however, an all-important matter requiring attention be- 
sides the form of vessel in which the soles are to travel, and that is, as 
* I attach great value to this use of sand, and always use it or an equivalent in 
all aquaria. The late Mr. W. Alfred Lloyd objected to it as likely to choke any fish, 
but I have never found it to do so; on the contrary, the gills keep themselves clear 
from its intrusion by their own action. 
