MOLLUSCA. 467 



Remarks. This species resembles T. eufaulensis in general 

 form and proportions, and in the keel-like extension of the shell 

 along the hinge-line back of the beak. From the internal casts 

 alone the two species can hardly be distinguished if at all, but 

 the external characters of the shell are quite different. The ribs 

 of the shell of T. ktimmeli are narrower, sharper and nodose, 

 and the interspaces between the ribs continue to the posterior 

 portion of the shell with about the same width, while in 7*. 

 eufaulensis the interspaces become regularly narrower posteriorly. 

 The zig-zag direction of the ribs across the upper portion of the 

 shell is also different from T. eufaulensis, in which species they 

 pass directly across this portion of the shell from the bounding 

 ridge below to the hinge-line. 



Formation and locality. Red Bank sand, Red Bank (116), 

 near Middletown (112), Shrewsbury River (119). 



Geographic distribution. New Jersey. 



Super-family PECTINACEA. 



Family PECTINIDAE. 

 Genus PECTEN Miiller. 



Pecten tenuitestus Gabb. 

 Plate L., Fig. 9. 



1861. Pecten tenuitesta Gabb, Proc. Acad. Nat. Sci. Phil., 1861, 



P- 3 2 7- 

 1864. Pecten tenuitesta Meek, Check List Inv. Foss. N. A., Cret. 



and Jur., p. 7. 



1868. Pecten tenuitesta Con., Cook's Geol. N. J., p. 725. 

 1886. Pecten planicostatus Whitf., Pal. N. J., vol. I (Monog. 



U. S. G. S., vol. 9), p. 48, pi. 8, figs. lo-ii. 

 1905. Pecten tenuitesta Johns., Proc. Acad. Nat. Sci. Phil., 1905, 



p. n. 



Description. Left valve depressed convex or nearly flat, equi- 

 lateral, and aside from the auriculations nearly subcircular in out- 



