LAMELLIBRANCHIATA. 347 



PaLjEONEILO truncata. 



plate l, figs. 40, 41. 



Palaoneilo truncata. Hall. Pal. N. Y., vol. v, pt. 1. Plates ami Explanations: PI. 50, figs. 40, 41. 1883. 



Shell of medium size, trapezoidal; length about twice the height; basal 

 margin nearly straight or slightly concave in the middle ; posterior margin 

 retrally truncate, acutely rounded above into the cardinal line, which is very 

 slightly arcuate. Anterior end rounded. 



Valves convex below, becoming gibbous in the middle and upper part. 



Beaks at about the anterior fourth, somewhat prominent, rising above the 

 hinge-line. Umbonal ridge broad, distinct. Post-cardinal slope depressed, 

 marked above by an undefined elevation near the hinge-line. 



Test thick, marked by fine, closely-arranged, concentric striae, which in 

 some parts are crowded and fasciculate, but which do not rise into regular 

 lamellar expansions. Interior unknown. 



The two specimens described measure respectively 30 and 24 mm. in 

 length, and 15 and 12 mm. in height. 



This species may be compared with P. muta, but it is a proportionally longer 

 shell, the basal and cardinal margins are nearly parallel, the beaks are more 

 anterior, and the shell surface is not raised in regular lamellar expansions. 



Formation and localities. In the sandstones of the Waverly group, at Rich- 

 field and Medina, 0. 



Palaoneilo sulcatina. 



PLATE I,, FIGS. 4-2-16. 



Nueulites gtdcatina, Co.«ir.\d. Jour. Acad. Nat. Sci., Phila., vol. viii, p. 250, pi. 15, fig. 10. 1842. 

 Leda nuculif<rrmis, Stevkns. Am. Jour. Sci., series 2, vol. xxv, p. 262. 1858. 



" Barrlti, Whitk ami Whitfield. Proc. Boston Soc. Nat. Hist., vol. viii, p. 298. 1862. 

 PcUwmeilo liarrini (Whitk and Whitkikld), Hall. Prelim. Notice Lamellibranchiata, 2, p. 11. 1870. 

 « .. X " " Pal. N. Y., vol. V? pt. 1. Plates and Explanations : 



PI. 50, figs. 42-46. 1883. 

 NuciUa HiMmrdi, Winchbll. Proc. Acad. Nat. Sci., Phila. 1862. 



Shell of medium size or larger, sub-elliptical or narrowly ovate ; length nearly 

 twice the height; basal margin regularly curving. Posterior extremity 

 narrowly rounded, with sometimes an obscure retral truncation. Cardinal 

 line gently arcuate. Anterior end regularly rounded. 



