NAPLES FAUNA IN WESTERN NEW YORK, PART 2 279 



description it is stated that this part of the shell is broken. As there is a 

 striking agreement in other points of structure, we may assume that the 

 species are fully congeneric. These shells however, while carrying the 

 general expression of Loxopteria, show some palpable differences from the 

 typical members of the genus, L. d i s p a r and L. 1 a e v i s. The subtri- 

 angular aspect of the shell is lost by the development of the postumbonal 

 slope on the left valve, carrying corrugations and showing no trace of wing, 

 and in the right valve the broad oblique depression is anterior, while the 

 posterior moiety of the valve is broadly convex instead of being abruptly 

 elevated into a winglike expansion. With more data these differentials 

 may become entitled to distinctive value. 



ontakia gen. nov. 

 (Cardiola auct. aliq.) 



Cardiola was proposed by Broderip in 1839 1 f° r shells typified by the 

 species C. interrupta Sow., an Upper Siluric shell having a subcircular 

 marginal outline, convex umbones with beaks projecting beyond the short 

 and straight hinge line ; cardinal (ligamental) areas triangular and rising 

 to the hight of the beaks, so that they are broadest in the interval 

 between the beaks ; this area is striated horizontally. The hinge line, so 

 far as known, is a straight edge without modification or denticulation. The 

 strong umbones are directed forward and give a general obliquity to the 

 convex contour of the shell. The surface is covered with strong radial ribs, 

 which are crossed, cancelated or knotted by concentric lines grooving the 

 surfaces of the radii without materially affecting the deep intervals. These 

 concentric markings usually develop into or express themselves as corru- 

 gations or undulations, specially strong over the umbonal region of the 

 valves. The shell is calcareous and relatively thick. 



These shells are of striking and peculiar external habit, and we under- 

 stand their variations in expression pretty thoroughly. Barrande has given 

 nearly 200 illustrations of Bohemian specimens of C. interrupta alone and 



1 Murchison's Silurian System, 2:617. 



