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tatives of most of the families of plectognaths (and nearly 

 modern acanthurids as well). The triacanthodids are 

 represented there by the Spinacanthinae, which 

 probably became extinct, and the Eoplectinae, which are 

 ancestral to the gymnodont families. The triacanthids, 

 derived from the triacanthodids, are represented by the 

 Protacanthodinae, in many ways intermediate between 

 the triacanthodids and triacanthids. The aracanids are 

 represented by Proaracana, not much different from Re- 

 cent genera, while the ostraciids, derived from the 

 aracanids, are also found in the Eocene beds of Monte 

 Bolca in the form of Eolactoria, again not much dif- 

 ferent from Recent genera. Among these scleroderms. 



