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Silverside Family 
                  Atherinidae 
  Only one species of silversides is known from Wisconsin. It is a strictly
freshwater form with an extensive range over the eastern United States. 
Hubbs (1921) suggested that its "habitat reactions" were inherited
from 
its marine ancestors and hence were developed in the sea. 
  Twelve species of silversides in eight genera are listed from the United
States and Canada (Robins et al. 1980). Of these, 10 occupy typical salt-
water coastal or estuarine habitats. Most silversides are small fishes. They
include the well-known California grunion, a spectacular fish which 
during high tide is thrown up onto the beach sands to spawn. Rosen 
(1964) demonstrated that the silversides, halfbeaks, and killifishes were
closely aligned families, probably with a common Eocene ancestry in the 
fresh and brackish waters of Australia, from which they spread around 
the world. 
  The members of this family have scaled heads, two dorsal fins (the first
small and spiny), pectoral fins high on the body, and both pelvic and 
anal fins each with a small spine. The swim bladder is present, but loses
its pneumatic duct connection with the pharynx (physoclist). 
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