Introduction 



The ostracode form genus "Bairdia" is probably the most over- 

 extended category in the entire suborder Ostracoda. It has been 

 applied with more or less serious intent to over 600 ostracode species 

 ranging in age from Ordovician through Recent (Howe, 1955; van 

 Morkhoven, 1963). Recently considerable progress has been made 

 toward a more reasonable and useful classification of Paleozoic (Sohn, 

 1960) and post-Paleozoic, especially Triassic (Kollmann, 1960, 1963), 

 fossil Bairdiidae. It has been generally agreed that the genus Bairdia 

 sensu stricto should be restricted to the Upper Paleozoic, for its 

 Carboniferous type-species B. curta McCoy and other closely allied 

 species ranging from Devonian through Permian (Sohn, 1960). To 

 include other forms under this name violates its morphologic and 

 quite possibly its phyletic homogeneity. 



At least 75 nominal species representing more nearly 200 morpho- 

 logic species of '^ Bairdia" have been recognized in the Recent; at 

 least as many species flourish undescribed in the rich and varied 

 shallow-water assemblages of tropical and subtropical regions, which 

 are still very poorly known. Thus "Bairdia" exemplifies today the 

 confusion and frustration expressed by "Cythere" and "Cythereis" 

 before 1925. The deceptively simple carapace morphology of this 

 group combines with the apparent variability to discourage efficient 

 discrimination of species. Probably three-quarters of all citations of 

 non-European species of "Bairdia" are misidentifications or homo- 

 nyms. This deplorable condition results in part from the difficulty of 

 describing accurately and diagnosticaUy the geometry of a smooth 

 carapace, but even more it reflects the relative unimportance ascribed 

 to "Bairdia" by many workers. Conversely, it is obvious that 

 "Bairdia" can have little significance as a paleoecologic or stratigraphic 

 index as long as its taxonomy remains unreliable. 



There is a recurrent "heresy" of obscure origin and little factual 

 substantiation to the effect that the "key" to relationships among 

 Recent ostracode species is to be found in the soft parts, and that the 

 carapace alone provides insufficient evidence for distinction of "bio- 

 logic" or "natural" taxa. Application of this principle to Recent 

 Bairdiidae has foUowed two courses: many taxonomists have admitted 

 that Bairdia s. s. is restricted to the Paleozoic, and that one or more 

 new genera need to be established for Recent forms, but they have 



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