42 
BULLETIN OF THE BUREAU OF FISHERIES 
available, and the last six papers listed in the bibliography were drawn upon freely. 
The keys form a sort of summary of tlie present state of knowledge of the characters 
of the eggs and young of the Sciaenidae of the Atlantic coast of North America. It is 
hoped that they will prove useful in the further study of the eggs and the young of 
this family of large fishes, most of the members of which are of much economic 
importance. 
It is evident from the present treatise that considerable gaps remain to be filled 
to make known fully the embryology and larval development of the Sciaenidae, 
though quite a number of stages in the development of several species, heretofore 
unknown, are described and figured. It has been particularly difficult to identify 
the eggs; and female fish, ripe enough for stripping, have been taken seldom. In a 
few instances the eggs were secured by confining nearly ripe females in tanks. How- 
ever, this procedure was successful only if the females were ripe enough to spawn 
the first or second night after capture. If not, the fish retained the eggs. It was 
shown by Hildebrand and Cable (1930, p. 418) that spots ( Leiostomus xanthurus), 
though containing advanced roe, retained it for several months after capture, that is, 
long after the spawning season had ended. The principal hope of securing the eggs 
for certain identification, therefore, lies in the capture of fully, or almost fully, ripe fish. 
The illustrations accompanying this report, unless otherwise stated, were prepared 
by the junior author, who also made many of the preliminary identifications and 
assisted in various ways in the study of the specimens. The senior author is respon- 
sible for the final identifications and the composition of the report. 
ARTIFICIAL KEYS TO THE EGGS AND YOUNG SO FAR AS KNOWN 
The following series of keys are entirely artificial, that is, they are designed to 
identify the fish rather than to show the natural relationship. The eggs of only 
three species of Sciaenidae from the Atlantic coast of the United States are known to 
date. A key by which the eggs of these three species may be identified is offered. 
The other keys are intended to identify the young of various sizes. The “Key to 
the newly hatched } r oung” is based on live specimens hatched in the laboratory. 
It is limited, therefore, to the three species for which the eggs are known. All the other 
keys are based on preserved specimens. The length of the newly hatched young 
given in some instances exceeds that of the specimens treated in the next key, not- 
withstanding that the “smaller” specimens (1.7 to 1.8 millimeters long) were older 
fish, as shown by their development. The apparent decrease in length no doubt is 
caused by shrinkage in the preservatives. Some of the species included in the keys 
for the larger size groups are missing in those for the smaller fish, because the smaller 
stages are not yet known. 
The size groups chosen for the keys are thought to be close enough together to 
make it possible to identify specimens of intermediate lengths. Specimens of lengths 
intermediate of those on which the keys are based should be identified by the key 
covering a range nearest their size. For example, specimens 11 millimeters long 
could be identified most readily by using the key for specimens 8 to 10 millimeters 
long, whereas specimens 14 millimeters long should be identified by using the key 
prepared for specimens 15 to 20 millimeters in length. Specimens exactly half way 
between two groups, in general, should be identifiable as readily by the key for the 
smaller specimens as by the one for the larger ones. 
