704 ZOOLOGICAL 
seventeen and one-half pounds. Two have died 
during the past summer, but the others seem to 
be in good condition. 
A census of the inhabitants of the Aquarium, 
made a short time since, showed the following 
numbers : 
Species Specimens 
VS HES aes cate oeee eee awe 108 2344 
Amphibians 11 107 
Rep bil cs eeeee eee 19 160 
IN ayaa) osha ee ee 2 4 
Imvertebrates) -2--2--------------— 24 815 
EEobil Sse fe ee es 164 3430 
18 (Cs Os 
CICHLID FISH AT THE AQUARIUM. 
N the fresh water rivers and lakes of Central 
and South America the members of the family 
Cichlidae take the place of our sunfishes and 
The species, which are very numerous, 
the related 
genera Cichlosoma and Heros. Our specimen 
proves to be Cichlosoma hedricki, (Meek), de- 
scribed by Dr. S. E. Meek in 1904 in his Fresh- 
water Tishes of Mexico. 
basses. 
are mostly referable to closely 
No species of this family have ever reached 
the New York Aquarium until the present sum- 
mer when (about the last of June) six small 
specimens arrived. These were purchased from 
a boy who brought them all the way from Vera 
The 
largest of the specimens at the time of arrival 
They 
were placed at once in one of our balanced 
When 
the specimens arrived their colors apparently 
Cruz, Mexico, in a two quart tin bucket. 
was about two and one-half inches long. 
aquaria where they have been ever since. 
were not fully developed, but they have grown 
rapidly in captivity and the colors have become 
brilliant, especially in the males. 
Fresh water fishes are not so well known as 
marine fishes for their ability to change their 
colors. This species, exhibits this 
phenomenon to quite a marked degree. The 
chromatophores or color cells not only have a 
however, 
remarkable range of contraction and expansion 
of the color granules for a fresh water fish, but 
they are under such control of the nervous sys- 
tem that they operate instantaneously. 
SOCIETY BULLETIN. 
The ordinary background coloration of oliva- 
ceous varies from dark olive to very pale olive, 
and this is often covered, especially on the 
head, with yellow, more or less bright. There 
are about eight vertical dark bands on the body 
besides four others across the top of the head 
and nape, and a dark lateral band extends back- 
ward from the opercle. There is also a dark spot 
at the base of the caudal fin. All of these dark 
markings vary exceedingly. Sometimes they 
are very prominent and again almost wanting. 
Frequently a prominent black spot appears sur- 
rounded by a lighter area on the middle of the 
side. The lateral band usually extends back to 
this spot but it may extend to the base of the 
tail or it may fade out until almost invisible. A 
brilliant blue color appears on the opercle, about 
the mouth and on the ventral fins, and this may 
disappear entirely. The vertical fins and the 
upper part of the body are beautifully flecked 
at times with an irridescent metallic blue and 
this may also vanish completely. 
There must, then, be at least four kinds of the 
chromatophores containing the yellow, green, 
blue and dark pigments, and these are all sepa- 
rately under the control of the nervous system, 
since the color changes may involve any one 
color only, or two or all at the same time. 
The majority of these color changes can hard- 
ly be explained by assuming that they are adap- 
tive to the surroundings. It is observed, how- 
ever, that the fishes become almost uniformly 
pale olivaceous, and suppress all bright and 
striking colors and marks when frightened. 
This change probably renders them less con- 
spicuous against the bottom and among vegeta- 
tion in their natural environment and adds to 
their chances for escaping when pursued by their 
enemies. In the absence of positive evidence, 
however, it is useless to speculate. 
A few of the cichlid fishes are herbivorous 
and have chisel-like teeth for the purpose of 
biting off vegetation, but the majority are car- 
nivorous and have pointed teeth. Our species 
belongs to the latter class, and will eat crushed 
clam and meal worms with avidity. 
They are among the hardiest fishes in the 
Aquarium, as far as crowding is concerned at 
least, for they have thriven and grown well in a 
small balanced aquarium. Though they were 
taken at a venture they have proved to be among 
the most interesting small fishes of our collec- 
tion. 1, (Ch, ©)» 
