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BEC 27 192f^ 



D. K. Greqer — N. American Species of Ether i^givxi. 635 



North American Species of the Brachiopod Etheridgina, 



By D. K. Geeger, Fulton, Missouri. 



(PLATE XIV.) 



npHE series of minute, adherent species of Bracliiopoda brought 

 -*- together in the following discussion are usually assigned by 

 American jDalaeontologists to the genus Strophalosia, but recent 

 writers have come to recognize the fact that, in America at least, 

 the genus Strojohalosia is a polyphyletic group. Dr. Stuart Weller, 

 in his monograph on the Mississippian BrachiojJoda (1914), all but 

 recognizes the generic value of these minute shells when he points 

 out the lack of harmony in the series of forms which he places in 

 the genus Strophalosia. 



Of the five American species here grouped under Oehlert's 

 excellent genus Etheridgina, the Strophalosia scintilla of Beecher 

 bears the closest resemblance to the genotype, Procluctus complectens 

 Etheridge. S. scintilla is abundant in the fauna of the Louisiana 

 Limestone (Kinderhookian) of Eastern Missouri, and my collection 

 contains over three hundred examples in various stages of develop- 

 ment — from minute spats 0"4 mm. in diameter to mature shells, the 

 average size of which seldom exceeds 2"5 mm. 



Recently, through the kindness of a Scottish correspondent, eight 

 well-preserved specimens of Etheridgina complectens (Etheridge), 

 from Fife, were placed in my hands for study and illustration, 

 and an examination of this material brings out the following facts — • 

 the presence of a cardinal area, a covered delthyrium, attachment of 

 the pedicle valve by cementation over the greater part of the 

 visceral area, instead of at the beak as in the true Strophalosias, 

 and that the clasping propensity of the spines is more apparent 

 than real. 



While fully appreciating the necessity of correct application of 

 a generic term, our study of these minute forms leads to the con- 

 clusion that it better serves the purpose of classification to group 

 under the genus Etheridgina the following so-called Strophalosias 

 from American strata. 



Genus ETHERIDGINA Oehlert. 



1877. Etheridgina, subgenus of Productiis. GenotyiDe E. complectens. In 



Fischer, Manuel de Conchyliologie, p. 1278. 



Etheridgina complectens (Etheridge). (PI. XIV, Figs. 1-3.) 



1876. Procluctus comphcten'^ R. Etheridge, jun.. Quart. Journ. Geol. Soc., 

 vol. xxxii, p. 462. 



1878. P. complectens R. Etheridge. jun., op. cit., vol. xxxiv, p. 498. 



From the published figures of this species I have reproduced two 

 of the figures of Mr. Etheridge, Fig. No. 1 from his paper of 1876 

 and Fig. No. 2 from the 1878 paper, since they best illustrate the 

 characters of the species as it is generally found. I have also 



