Maryland Geological Survey 613 



BucHiOLA retrostriata (v. Buch)' 

 Plate LX, Figs. 1-3 



Description. — The specific name of this shell entered into literature 

 as long ago as 1832 when von Buch used the name Venericardium retro- 

 striatum for shells from the upper Devonian of Biidesheim. With what- 

 ever generic name this specific term or the term palmatuvi employed by 

 Goldfuss has since then been combined, whether Avicula, Cardiola, Glyp- 

 tocardia or Bucliiola, the expression was in effect a generic one until the 

 date of Beushausen's careful analysis of the German species of Biichiola 

 and the differentiation of the typical B. retrostriata. The American 

 species of the genus, derived from the Devonian and in the main from the 

 characteristic horizon at the base of the upper Devonian (Intumesccns 

 zone) have had a similar history. The name Avicula speciosa was first 

 applied to them by Hall in 1843 and he subsequently introduced the 

 generic term Glyptocardia for the species though too late for recognition, 

 as Barrande's Bucliiola was already in the field. The identity of the New 

 York and European shells was recorded in 1891 by the writer who has 

 since that date been enabled to determine in part, at least, the substantial 

 local variations of the American shells Avhieh have heretofore been con- 

 cealed under v. Buch's name. 



Bucliiola retrostriata, the original and typical species, is distinguished 

 from other species of the genus by the following combination of charac- 

 ters. It bears 12-15 ribs which have elevated margins, more or less de- 

 pressed, and flat summits which are crossed by pretty strong retrally 

 curved or often chevron-shaped ridges, not traversing the line-like mar- 

 gins, and often varying in strength in different parts of the shell. The 

 condition exhibited in one of our figures which is that of an old shell is 

 quite characteristic of the species, showing the variation in the strength 

 of these concentric mai'kings, subdued in early age, strongest at maturity 

 and again declining in strength about the margins of the old shell. The 

 furrows between the ribs are narrow, flat and always smooth. These 



* For synonymy see Clarke, Naples Fauna in Western New York; N. Y. State 

 Mus., Mem. vi, p. 292, 1904; for figures, idem, pi. x, figs. 1-14. 



