NAPLES FAUNA IN WESTERN NEW YORK, PART 2 277 



by Barrande to his genus Sluzka. Some of these shells, e. g. S. arachn e, 1 

 show traces on the internal cast of the hinge line which suggest that they 

 were taxodonts. Barrande, however, regarded the hinge as devoid of 

 teeth. It is however observable that the majority of these shells, repre- 

 sentative of which we may cite S. amygdalina [pi. 358] from Etage G, 

 are of very primitive aspect and subcircular outline, with concentrically 

 striated or irregularly rugose surface, having prominent larval shells pro- 

 jecting at the apexes and also likewise devoid of evidence of hinge modifica- 

 tions. Similar characters, too, are seen in some of the species referred by 

 Barrande to his genus Vevoda, as for example V. expectans [Barn 

 pi. 13], in which the large size of the prodissoconch is specially notable. 

 Some of the more regular suborbicular shells of this kind suggest the genus 

 Paracyclas Hall ; and Neumayr has put under the latter both Vevoda and 

 the Paracyclas and Isocardia of Barrande. It is however clearly evident 

 that the shells we have now to consider are not species of Paracyclas, for 

 the normal forms of that genus from the Hamilton fauna have a very 

 distinct aspect in the character of the surface markings, the regularity 

 of outline and absence of the general primitive expression of these later 

 shells. To employ Barrande's term Sluzka for certain lamellibranchs in the 

 Intumescens zone is not necessarily to admit the integrity of that genus nor 

 to concede the reappearance in the upper Devonic of the Siluric types to 

 which the name was first applied. The employment of the term obviates 

 the erection of a new name ; and, in the absence of definite hinge structure 

 or, rather, with .present evidence of the extreme simplicity of the hinge, we 

 find in these Devonic shells an approximation to the structure represented 

 by the majority of Barrande's species of the genus. 



Loxopteria (Sluzka) corrugata sp. nov. 



Plate 14, fig. 18-26 



Shells of medium or small size, subcircular to subquadrate, general 

 aspect of left valve suggestive of Paracyclas. Beaks nearly median, 



1 Barrande. Syst. Sil. 6, pi. 265-1, fig. 8, 9. 



