NAPLES FAUNA IN WESTERN NEW YORK, PART 2 305 



species and has been found in New York only in the Styliola limestone 

 on Canandaigua lake, but it occurs also in the Naples fauna of Allegany 

 county, Md. 



Genus praecardium Barrande. 1881 



The shells for which Barrande established this genus are extremely 

 well characterized by their oblique form, truncated anterior extremity and 

 simple, sparse ribs, generally narrow and rectangular in cross section, with 

 broad intervening furrows. We find, however, that apart from these 

 typical forms there are variations in all of the essential details which 

 indicate deviation from the type toward structures common to Ontaria, 

 Buchiola etc. Thus while the upper Devonic fauna under discussion 

 contains an abundant localized development of the typical species, P. v e t u s- 

 tu m Hall, there are other forms which it is necessary to separate from this 

 species, in which is presented a more or less sharp duplication of the ribs 

 and somewhat less oblique form and yet no variant sufficient to withdraw 

 the species from the genus. The most widely distributed of the species is 

 the Praecardium v e t u s t u m, which has been identified by Beushau- 

 sen in the lower Upper Devonic of Westphalia, but in America has not been 

 found outside the western Portage subprovince in the vicinity of Lake Erie. 



In regard to the structure of the hinge in Praecardium, Barrande repre- 

 sented a rather high area bearing a number of vertical riblets which 

 terminate at the hinge line in denticles. Though these were characterized 

 by him as "teeth," it has been suggested by both Neumayr and Conrath 

 that they are actually representatives of the radial ribs of the surface 

 extending about and beneath the beak and their interlocking terminations 

 and, though homologous with teeth, are not analogous thereto. The 

 structure represented both by Barrande and Conrath is parallel with what 

 we have occasionally found, with other writers, in species of Buchiola, and 

 have elsewhere discussed, but whether or not these exist in the typical 

 Bohemian species of Praecardium, our observations are in entire accord 

 with those of Beushausen, who remarks that in the best preserved speci- 

 mens of P. vetustum from the Rhenish Devonic there is no trace what- 



