164 
ORIGIN OF LIFE IN AMERICA 
affinity between Europe and North America is so strong, 
and already so many instances of this relationship have been 
referred to, that nothing short of a wide and convenient land 
bridge with lakes, rivers and mountains will suffice to ex¬ 
plain the meaning of the palaeontological facts. All we know 
is, that in early Tertiary times these fishes multiplied and 
migrated from their original centre of dispersal. The genus 
of the bow-fin is all but extinct. Only a single species 
remains. The bony-pikes exhibit a little more vitality, no 
less than three species being still living. The common form 
(Lepidosteus osseus) ranges from the Great Lakes to Vermont 
in the east, and from there south-westward as far as Mexico. 
A much larger bony-pike lives in the southern States, in 
north-eastern Mexico and in the island of Cuba, while a 
smaller species (L. tropicus) has been observed in Tabasco, 
Guatemala, Nicaragua and Panama.* If Lepidosteus were a 
fish directly limited to fresh water, we might argue that at 
some remote time in the past, a land mass extended from 
Mexico to Cuba and southward to Panama, but being occa¬ 
sionally met with in brackish water it is possible that bony- 
pikes can traverse short distances by sea. We cannot for this 
reason base any conclusions regarding minor changes of land 
and water on the present distribution of these fishes. Never¬ 
theless it is a significant fact that the western States are 
devoid of bony-pikes and perches as they almost are of fresh¬ 
water Unios. 
Besides the Mississippi fauna, the curious dwellers of sub¬ 
terranean waters in the Mississippi drainage area throw a 
certain amount of light on the past conditions of the country. 
A brief account of them at any rate will be of interest before 
concluding this chapter. 
I believe Mr. Putnam f was the first to exhibit a collection 
of blind fishes and crustaceans from the Mammoth Cave to a 
scientific meeting. In doing so he expressed the opinion 
that most of the animals inhabiting the cave are of compara¬ 
tively late introduction, since they are closely allied to forms 
* Regan, C. Tate, “Biologia Centrali-Americana,” p. 181. 
t Putnam, F. W., “ Mammoth Cave and its Inhabitants,” pp. 194 — 
195. 
