72 
ZOOLOGICAL SOCIETY BULLETIN 
IIOATZINS IN THEIR CAGE; KARTABO 
These are the first of their kind ever to be kept alive in captivity. 
Photograph by John Tee-Van 
are interested but not alarmed at what goes on 
around them, and one which lost its tail in the 
flurry of capture is sprouting out new feathers; 
all signs of satisfactory conditions of life after 
six weeks of captivity. 
THE LAND MINNOW OF KARTABO* 
By John Tee-Van 
Assistant, Tropical Research Station 
Illustration by author 
F ROM an evolutionary standpoint the emer¬ 
gence of animals from their original 
aquatic home, marks a significant period 
in the development of the higher forms of life. 
The adoption of a new, dryer habitat was first 
accomplished among the higher animals, as far 
as we know, by the amphibians, who emerged 
from the water along the shores of the primeval 
seas and marshes in the Devonian period, twenty 
millions of years ago. 
At Kartabo, this change of environment from 
water to air is shown by a number of species of 
fish, notably by some of the armored catfish, 
* Tropical Research Station, Contribution No. 116. 
Plecostomus, and by various species of the genus 
Rivulus. 
The genus Rivulus as represented in Guiana, 
contains a number of dull, rather elongate, al¬ 
most cylindrical, flat-headed fish of small size. 
They rarely reach three, and are usually from 
one to two inches in length. There is a single 
dorsal fin, placed far back on the body, quite 
near the tail. The tail is usually rounded and, 
in a number of species, carries near its base a 
black ocellus. In most of the species the males 
are less brilliant than the females. The only 
one so far found at Kartabo is Rivulus stagnatus 
Eigenmann. 
These fish are commonly called “Tooth- 
Carps” and belong to the same group as the 
killifishes of the northern United States. They 
are included in the order Microcyprini and as¬ 
signed to the family P oecilndae ,—a group which 
includes the interesting viviparous fishes Poe- 
cilia, found in great numbers in the streams and 
canals of the coastlands of Guiana, and ex¬ 
tremely important to man by reason of their 
destruction of untold numbers of mosquito 
larvae. Because of their great multitudes these 
