MOLLUSCA. 649 



tion of the tube was also originally preserved, but this has been 

 partially destroyed in removing the shell. The tube differs from 

 those in the Vincentown limesand which have been described as 

 G. americana, and of which the shell has never been observed, 

 in its less slender form and in the absence of the conspicuous, 

 irregular annulations. 



Formation and locality. Navesink marl, Bruere's pits, near 

 Walnford (195). 



Geographic distribution. New Jersey. 



Gastrochaena linguiformis n. sp. 

 Plate LXXIIL, Fig. 9. 



Description. Tube of the type specimen with a diameter of 

 1 1 mm. Dimensions of the right valve : height 7.3, mm. ; length, 

 about 19 mm. Valves of the shell linguiform, the dorsal and 

 ventral margins nearly straight and subparallel, the posterior 

 margin regularly rounded, the anterior margin not preserved in 

 the type. Right valve gently convex throughout, the left valve 

 a little more convex and somewhat twisted. Valves marked by 

 concentric lines of growth. 



Remarks. This species may be easily distinguished from G. 

 whitfieldi by its more elongate and linguiform valves and the 

 rounded posterior margin. 



Formation and locality. Merchantville clay-marl, near James- 

 burg (140). 



Geographic distribution. New Jersey. 



Gastrochaena americana Gabb. 

 Plate LXXIIL, Fig. 13. 



1860. Gastroch&na Americana Gabb, Jour. Acad. Nat. Sci. 



Phil., 2nd ser., vol. 4, p. 393, pi. 68, fig. 20. 



1861. Gastroch&na Americana Gabb, Synop. Mbll. Cret. Form., 



p. 180 (124). 



1 86 1. Polorthus Americana Gabb, Proc. Acad. Nat. Sci. Phil. 

 . 367. 



