256 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
A careful study of many specimens shows that in the same species 
from different localities some differences are noticeable. These differ- 
ences are not individual variation, neither are they constant enough 
to constitute distinct species, nor will the conditions permit of their 
being called subspecies. They are rather group differences, constitut- 
ing what perhaps may be termed geographical races. 
It might be asked what is meant by ‘‘ geographical race.” This is 
difficult to explain, but as intended to be understood here is, as said 
before, a group of slight variation not satisfying the conditions of 
species or subspecies—these two being interpreted as (1) a form 
between which and another closely related form a structural gap exists; 
(2) one of two closely related forms, one of which has sprung from the 
other, between which there is no gap, but the differences grade into 
each other through different localities. A subspecies may be termed 
an incipient species. According to this definition, then, a ‘‘ race” may 
be called an incipient subspecies; in other words, an indication of how 
a subspecies may originate—through some change in environment. 
To illustrate: JZ peninsula, occurring at Pensacola (the type locality) 
and at Indian River, Florida, each locality group differing somewhat 
from the other should intergrade through successive localities to form 
a subspecies at Indian River. As a matter of fact, they can not be 
told apart; but intermediate groups, occupying localities of somewhat 
different conditions, differ slightly as groups but not always suf- 
ficiently as individuals to cause even a suspicion of another species. 
There may even be groups intervening which do not differ from the 
typical species. 
Key to the species of Menidia of the east coast of the United States. 
(This key will apply exactly only to those close to the typical examples. Difficulty will be found 
with the intergrading or mixed forms.) 
a. Anal rays 15 to 17, rarely 19; scales 38 to 41. 
b, Snout equal to or longer than eye; anal base shorter than head. 
c. Body generally deep, depth 4.5 to 5.5 in length to base of the caudal. Light colored; 
often somewhat speckled on sides; large salt-water form. Eastern Florida to 
MP ORAS ve cicicy we cetninsin SRES See we ae Eee eee a eee ee ene eer eee eee M. peninsule. 
cc. Body generally slender, depth 5 to 7 in length to base of caudal; small fresh-water forms. 
d. Origin of spinous dorsal nearer base of caudal than tip of snout; depth 6. Small, light 
colored, fresh-water form. Lower Mississippi Valley ....-.--------- M. audens. 
dd. Origin of spinous dorsal midway between tip of snout and base of caudal; * depth 5 to 7. 
Small, usually dark colored, fresh-water form. Florida. 
: M. peninsulx atrimentis. 
bb. Snout mostly shorter than eye; anal base longer than head; body compressed laterally. Poto- 
mace Rivertse st .* oe Sse. ee Muse eR seca cee ee ence M. beryllina. 
e. Snout blunter than the above; body rather round and caudal peduncle usually 
shorter. Coastwise, Massachusetts to South Carolina......--. M. beryllina cerea. 
aa. Anal rays 20 to 27; scales 39 to 50-8 to 10. 
jf. Origin of spinous dorsal nearer base of caudal than tip of snout; scales 39 to 45- 
1 0) ts ee ee ae ee ere ieee i ed BO ne A is JABS SaG6I6 7 M. menidia. 
jf. Origin of spinous dorsal about midway between tip of snout and base of caudal; 
scales’45toib0=8 to Oi. 5 Seb Foss. oe se cee eee ote senor aeee M. menidia notata. 

*This character holds strictly good in our typical specimens from the east coast of Florida and St, 
Johns River, but the majority of those from ‘‘ Salt Lake,” west coast of Florida, have the fin, some~ 
what nearer caudal, in this respect approaching M. audens. 
