80 PALEONTOLOGY OF NEW JERSEY. 



the other. Hinge in the left valve with a .small triangular tooth beneath 

 the beak, which is nearly direct, and a very distinct lig-amental pit which 

 is nuich elongated and very oblique. 



Only two specimens of this shell, both left valves and both imperfect, 

 have been observed. The length is less than half an inch. I have been 

 unable to identify it with any described species, recent or fossil. 



Localiti/: In the gray marls of the Miocene at Shiloh, N. J. From the 

 cabinet of the National Museum. 



Abba aequalis. 

 Plate XIV, tigs. 11-15. 



Amphiilenma aequalis Say: Jour. Acad. Nat. Sci. Phila., 1st ser., vol. 2, p. 307; Am. 



Couch., PI. XXVIII ; Courad, Miocene Poss., p. 76, PI. XLiii, fig. 9; Tuomey aud 



Holmes, Plioc. Foss. S. Car., p. 93, PI. xxiii, fig. 3. 

 Ahru aequalin (Say) Courad: Proc. Acad. Nat. Sci. Pbila., 1862, p. 574; Meek, Check 



List Miocene Foss., p. 11. 



^^ Shell orbicular, slightly oblique, pohshed, white, with very minute 

 and numerous concentric wrinkles near the margin, which are obsolete on 

 the disk and umbo; lateral teeth none, primary teeth two in the left valve 

 and one in the other; interior ligament cavity subfusiform, as long as the 

 exterior ligament." (Say's description of recent shell.) 



A few very perfect specimens of this species have been obtained, the 

 characters of which are so perfectly similar to those of the living shell as 

 to leave no question of their identity. They vary somewhat among them- 

 selves in regard to the relative position of the beaks, but the recent forms 

 present the same differences. The shells are thin and fragile, and only 

 moderately convex, of a broad-ovate form in outline, the beaks at about 

 one-third of the length from the anterior end, small and inconspicuous, with 

 a low inconspicuous ridge passing from them to the antero-basal margin, 

 and the surface marked by very fine, concentric, somewhat wrinkled lines 

 or ridges. In the interior the cardinal tooth is small, and the laterals rather 

 large, ligamental pit narrow, very oblique and of moderate length. It is 

 a very neat and jn-etty shell, and moderately abundant. 



Formation awl locality: The specimens are from Jericho, N. J., and 

 beloncf to the National Musinini ('(illection. 



