74 
BULLETIN OF THE BUREAU OF FISHERIES 
regalis, as noted below. The other characters given by him are apparently of no 
significance. 
Instead of being hard to distinguish, as has been asserted, Cynoscion nothus 
is, in fact, readily separable. The present extensive study has revealed three striking 
characters that prove conclusively that this species is distinct, and by means of which 
a single individual may be identified readily; namely, (1) the number of vertebrae, 
(2) the correlation of the numbers of soft dorsal and anal rays, and (3) the absolute 
number of anal rays. 
Counting the vertebrae of many individuals has shown that their number furnishes 
a valuable and positive character for differentiating this species from the other two. 
In the specimens of Cynoscion nothus counted there were always 27 vertebrae, except in 
one, which had 26. This was a small specimen from off the coast of North Carolina. 
Altogether 114 specimens of this species from the Gulf and Atlantic coasts were 
counted. Cynoscion regalis and C. arenarius invariably were found to have 25 
vertebrae. Fifty-five specimens of these two forms were counted and recorded. 
The counts were made after the mass of muscles had been removed from one side. 
The first vertebra, which articulates with the skull and has a different shape than the 
succeeding vertebrae, and also the hypural were included in the count. 
A study of the correlation of the numbers of dorsal and anal soft rays is what first 
led me to suspect that two distinct species were being confused under the name sand 
trout on the Texas coast. Table 1 shows this correlation in specimens from various 
localities on the Gulf coast. A mere glance at the table is sufficient to show that we 
are dealing here with two distinct forms, one having a shorter anal in combination 
with a longer dorsal than the other. Table 2 shows the same correlation for specimens 
from various localities on the Atlantic coast. Those specimens having the short 
anal in conjunction with a long dorsal also have 27 vertebrae and consequently are 
Cynoscion nothus. Comparing Tables 1 and 2 for Cynoscion nothus it may be seen 
that there is a tendency to an increase in the number of fin rays on the Atlantic coast. 
However, an increase in the number of rays in northern localities is a common 
phenomenon occurring among fishes having a wide latitudinal distribution. It may 
be noted that the increase occurs both in the anal as well as the dorsal, and the differ- 
ences are not marked enough to be of specific significance. 
For practical purposes merely counting the anal rays is sufficient to determine 
nothus. From an examination of Table 1 it will be seen that there is virtually a 
break in the series of 217 specimens enumerated, as far as the number of anal rays 
is concerned, except for 12 individuals. Every one of these 12 specimens was 
dissected and found to have 25 vertebrae, which placed them definitely with arenarius. 
The number of specimens examined is sufficient, for practical purposes, to enable 
us to make the statement that in Gulf waters nothus has 8 or 9 soft anal rays, while 
arenarius has 10 to 12. Similarly, Table 2 shows that for Atlantic coast fish there 
is a virtual break in the number of anal rays even more pronounced than in Gulf 
specimens, there being only 5 of 259 Atlantic fish examined that may be said to be 
intermediate. Of these 5 specimens 4 were found to have 27 vertebrae, which 
places them unquestionaly with nothus, and 1 had 26. This is the only individual 
of all those examined for vertebrae (169 in all) that had 26, all the others having 
either 25 or 27. It is a small specimen, having a standard length of 49 millimeters, 
taken at Beaufort, N. C., on September 29, 1926. Since on the same trip many 
others of similar size and presumably in company with it were taken, which 
