FRESH-WATER FISHES OF NEW JERSEY. 103 
tion to the fauna of Mercer County, and of New Jersey, about 
the time of its discovery by Baird we believe. Few in 
numbers at first, it has steadily multiplied until now it is 
fully as common in a few streams as the P. aureus is in 
many others. 
To pass now from quiet shady waters to the rapid hill-side 
brooks, let us discuss the active little cyprinoid, called, by 
Girard, Cyprinella analostana, and shown by Professor Cope 
to be the Hypsilepis anulostanus. This little fish, we know, 
was not a common species, we doubt if it was an inhabitant 
of our waters at all twelve years ago ; and now four-fifths of 
the streams, besides the shallow rapid waters above the falls 
in the river, are literally full of them. Discovered by Kirt- 
land in 1845, in the Ohio, did they work their way from 
there to here, or how became they so abundant in New Jer- 
sey, we might say, suddenly? If they were throughout the 
past century, say, a resident of our waters, with so few indi- 
viduals of their species in existence as to escape detection 
or to be confounded with others, what caused their numbers 
so suddenly to increase, that now they are taking the place 
of the old-fashioned Red-fin ( Hypsilepis cornutus) ? 
In the absence of any facts to the contrary we have 
jumped at the conclusion, that these "newer species” were 
to us, "newer creations.” If created of old then some un- 
detected alterations in our waters must be going on that 
some few years since gave them an impregnable advantage 
in the struggle for existence, and which will give other spe- 
cies now overlooked, ultimately, a similar advantage. Grant- 
ing this why do we not come across the few specimens that 
are now merely preserving their kind until the favorable 
moment arrives for their assuming a multitudinous existence? 
As far as we know the "rare" species of the present have 
somewhere localities where they are abundant, and those 
with us are those that are "pioneering," and are always in 
direct communieation with the river basin — the mass of 
their species dwell. 
