I90 NEW YORK STATE MUSEUM 



Anastrophia iiiterplicata (Hall) (Fig. 101). Atrypa inter- 

 ID 1 i c a t a Hall (1852. Pal. N. Y. 2:275, pi. 57) 

 Distinguishing characters. Extremely con- 

 ' i ""' ' vex; brachial valve the deepest; moderate sinus 



and fold; from two to three plications in the 

 former and three to four on the latter; lateral 

 plications increase by implantation. 



Fig. 101 Anastrophia inter- ' 



P Iic ata Found in the Clinton lenses, and in the lower 



and middle Rochester shale at Niagara. Also in the shale at 

 Lockport (Hall). - ^ 



Anastrophia brevirostris Hall (Fig. ; 



102) Atrypa brevirostris W 



Hall (1852. Pal. N. Y. 2:278, pi. 58) 



Distinguishing characters. Wider 

 than high; strongly convex; brachial 

 valve deepest; short nearly equal beaks; 



1 1 ■ r ,• • . 1 . 1 r Fig. 102 Anastrophia brevirostris 



sharp bifurcating or interpolated plica- 

 tions, from five to six in the sinus and fold, which are broad and ill 

 defined. 



Found in the lower Rochester shale at Niagara (?). Also in the 

 shale at Lockport (Hall). 



Genus pentamerus Sowerby 

 [Ety. : nivre, five; p.ipo<s, part] 

 (1813. Sowerby. Mineral conchology, 1 :j6; Hall & Clarke. 1893. 



Pal. N. Y. v. 8, pt 2, p. 236) 



Shell strongly inequivalve, biconvex with highly arched pedicle 

 valve; surface smooth, or with a few broad and obscure radiating 

 undulations. Under the beak of the pedicle valve is a deep and 

 narrow spoudylium, or plate with an excavated spoon-shaped cavity, 

 supported by a high vertical septum of variable length; brachial 

 valve with a pair of septa, the interior of the shell being thus di- 

 vided into five compartments. 



Pentamerus oblongus Sowerby (Fig. 103) (Hall. 1852. Pal. 

 N. Y. 2:79, pi. 25) 



Distinguishing characters. Very large and oblong, varying in out- 

 line with age; wider- in anterior part; valves strongly convex at 

 beaks; beak of pedicle valve overarching; subtrilobate division of 



