290 
ORIGIN OF LIFE IN AMERICA 
number of absentees and peculiar species among the birds, 
as in other groups. Dr. Chapman* is evidently puzzled how 
to account for the avifauna. Nevertheless, he makes the 
remarkably suggestive statement that if it could be shown 
that Central America was cut off from both continents at the 
time when it was joined to the West Indies, the origin of the 
island fauna could be explained in a satisfactory manner. 
That is precisely, I think, what did happen, as I have indicated 
above. 
Cuba presents some special aspects of interest. We have in 
the first instance quite a remarkable assemblage of fossil 
mammals. Western Cuba, with its extensive limestone dis¬ 
tricts, abounds in caves, many of which contain stagnant 
water or running streams. One of the most remarkable fea¬ 
tures of these subterranean waters is that they are tenanted 
by two kinds of fishes belonging curiously enough to a family 
of deep-sea forms (Brotulidae). These species, Stygicola 
dentatus and Lucifuga subterraneus, moreover, are blind, 
as might be expected from their habitat. Another typically 
marine genus, Atherina, possesses a single fresh-water species 
(A. evermanni) which is only known from western Cuba. 
Whether the presence of these marine species in fresh water 
implies that western Cuba had been submerged below sea- 
level is a debatable question that need not be further pur¬ 
sued. Other Cuban fresh-water fishes are forms often found 
in brackish water, or marine forms migrating into fresh water. 
Besides these there are two species of Heros, a Symbranchus, 
a Lepidosteus and one Agonostomus, all of which belong to 
purely fresh-water groups that could only have reached Cuba 
by means of a continuous system of lakes and rivers between 
the mainland and the island. Heros tetracanthus and Heros 
nigricans are members of the family Cichlidae, which has a 
wide range in South and Central America, only a single 
species entering the United States. Agonostomus monticola 
has a wider distribution in the West Indies, and is also met 
with in Mexico. Lepidosteus tristoechus lives in Mexico and 
the southern States, while Symbranchus marmoratus is widely 
distributed in the fresh waters of tropical America. If, as 
* Chapman, F. M., “ West Indian Bird Life,” p. 330. 
