BULLETIN OF THE UNITED STATES FISH COMMISSION. 215 
during the severest winter weather, never falls below 50°* This is 
really a. spring temperature, and I have with my own eyes seen small 
shrimps reproducing in winter as well as during the other seasons of the 
year. I doubt whether there is any other place as highly favored by 
nature for raising salmonoids, and also cyprinoids (tench, barbel), and 
crawfish. 
Where the small shrimp is not found and the water contains particles 
of lime, attempts should be made to introduce it and favor its repro- 
duction. 
53.— AMERICAN SILVER PERCH, ©IS CAH.SCO BASS. 
By GILBERT DUCL.OS.* 
M. Emile Bertrand has recently sent to the Fish Culture Establish- 
ment of the Zoological Garden of Acclimatization a number of Ameri- 
can silver perch, or calico bass ( Pomoxys sparoides ), born in a pond be- 
longing to him in the vicinity of Versailles. 
The reproduction of this species in 1888 was very considerable, for 
not only the three-year- old fishes, but even those born in 1887 have 
yielded an enormous number of eggs from which young calico bass were 
developed. The three-year-old fish living in M. Bertrand’s pond are 
now about 7J inches long and inches deep. The first spawning fish 
were imported directly from America. M. Bertrand had 25 of them. 
On account of the fatigue of the voyage only two males and a number 
of females survived. 
The spawning of the first year, 1887, yielded M. Bertrand more than 
500 fry, some of which were given to various members of the Acclima- 
tization Society ; others were sold. The flesh of the calico bass strongly 
resembles that of our European perch (Perea fluviatttis). After the 
spawning of 1888 M. Bertrand estimated that he had many thousands 
of calico bass. At the time of spawning, more than a hundred nests 
have been observed which have been placed in water about 8 inches 
deep. Evidently this species loves heat. The spawning places most 
sought after for the nests were the stone steps descending into the pond. 
The water being shallow the steps receive the sun’s rays, retaining the 
heat to the advantage of the fishes. 
The adult fish does not fear the cold. M. Bertrand, desirous to learn 
whether the calico bass would thrive in impure waters, placed a mini 
ber of the young in a little pool which received waters full of impuri- 
ties, and of which the temperature rose to above 77 degrees Fahrenheit. 
In spite of these unfavorable conditions the calico bass have prospered 
and have increased rapidly. Individuals which were ■£ of an inch long 
in April, when they were placed in this pool, measured 3^ inches in 
the following August. 
*La Perche Argent6e d’Am6rique ou Calico Bass. From Revue des Sciences Nat- 
alies Appliqu^es No. 1, January 5, 1889, p. 12. Translated by Dr. T. H. Bean. 
