104 Cincinnate Soctety of Natural Fhstory. 
NEW AND LITTLE KNOWN AMERICAN PALEOZOIC 
OSTRACODA. 
By Hy OAUiRTcH. 
(Read February 4, 1890.) 
INTRODUCTION. 
In offering the following extensive additions to the known forms 
of American Paleozoic Ostracoda, it may be in place to explain 
how it happens that my cabinet is so rich in a class of fossils that 
is usually but meagerly represented in even the best of our public 
and private collections. The last fact is no doubt due, primarily, 
to the small size of most of the forms, some of the species of 
Leperditia and Lsochilina, only, being large enough to come within 
the observing powers of the average collector. By their mere 
abundance, some of the smaller forms have long ago forced them- 
selves upon him, but the more modest majority require great care 
and more laborious methods than are now in common use, to 
obtain. 
Most of the smaller species so far published and illustrated have 
been described by English authors, of whom Holl, Kirkby, Brady 
and Jones, the last particularly, have made the study of the Os¢ra- 
coda a specialty. 
The American material at their command was unfortunately 
rarely very ample, consisting only, in most cases, of specimens 
attached to slabs of shale and rock. Being unwieldy, these are 
often difficult to study, while important characters also may be 
hidden by the matrix. ‘Their work, however, is as good as it was 
possible to make it under the circumstances, their descriptions 
being fortified by good illustrations, enabling the student to 
identify their species and varieties with comparative ease in nearly 
every case. 
Good figures are an absolute necessity in the study of this inter- 
esting though difficult group of organisms. Where so much 
depends, as in these fossils, upon outward form and other peculiar- 
ities that must be expressed by terms having, perhaps, quite differ- 
ent values with different authors, and where there is often no little 
