96 BULLETIN FLORIDA STATE MUSEUM Vol. 8


 INTRODUCTION
 Of the many species of cyprinid fishes inhabiting eastern North
America, few are better known to the layman than the Common Shiner,
Notropis cornutus. This is due to its abundance, wide distribution,
large size, and striking coloration. Nevertheless the systematic re-
lationships of the forms referred to this and to closely related species
have long perplexed students of North American freshwater fishes.
 The group that includes Notropis cornutus and its most closely
related forms (here referred to as the subgenus Luxilus) is in a rel-
atively early stage of evolution. Within the Luxilus complex may be
found all stages of speciation, and in at least two cases considerable
subjective judgment is needed to determine whether forms are in-
cipient or actual species. The Luxilus group thus furnishes an ex-
cellent opportunity for observing and understanding the basic proc-
esses of change which occur during evolutionary history.
 The members of the subgenus Luxilus have had an unstable no-
menclatural history. Their recent evolution and consequent close
inter-relationships have made the arrangement of species difficult.
D. S. Jordan, who was mainly responsible for previous attempts to
classify these groups, moved species back and forth among genera
and subgenera, usually with little apparent reason.
 Although morphological criteria have been the primary bases for
the resolution of various taxonomic problems encountered in the pres-
ent study, zoogeography, ecology, and clinal variation also have been
taken into account. This has resulted in the recognition of 8 species
and 1 subspecies instead of 6 species and 4 subspecies as in the cur-
rently accepted classification. Both arrangements are listed below.

 Current classification Proposed classification
 coccogenis group
Notropis coccogenis (Cope) Notropis coccogenis (Cope)
Notropis zonistius (Jordan) Notropis zonistius (Jordan)

 zonatus group
Notropis zonatus zonatus (Agassiz) Notropis zonatus (Agassiz)
Notropis zonatus pilsbryi Fowler Notropis pilsbryi Fowler

 cornutus group
Notropis cerasinus (Cope) Notropis cerasinus (Cope)
Notropis cornutus cornutus (Mitchill) Notropis cornutus (Mitchill)