232 ANNALS NEW YORK ACADEMY OF SCIENCES 



above, subangular on the periphery, about one third of the upper surface 

 depressed by contact with the preceding volution. The volutions are em- 

 braced up to the keeled periphery, so that the top of the shell is nearly flat. 

 Suture scarcely depressed. Umbilicus probably closed. Surface without 

 ornamentation. 



Platyceras subelegans sp. nov. 



Shell small, rapidly enlarging, completing about one half a turn, more 

 strongly curved at the apes, but very slightly spiral, broad on the outer side, 

 contracting toward the inner, so that the section is subtriangular ; marked by 

 numerous longitudinal plications, especially by a narrow peripheral carina 

 defined by two deep sulci and more persistent toward the apex than the 

 others. Surface crossed by lamellose concentric lines whose direction is made 

 very sinuous by the plications. 



Orthonychia compressa sp. nov. 



Shell of medium size, oblique, conical, compressed, nearly complanate or 

 bilaterally symmetrical, very rapidly enlarging and slightly bent, making one 

 half 8. volution or less. Cross section subelliptical, very much longer than 

 broad. Surface nearly smooth, marked only by obscure sublamellose growth 

 lines. No costse or spines. 



Two specimens have been included in this species, each having certain 

 individual peculiarities. The larger contracts distinctly toward the outer 

 or convex edge of the shell, while the smaller is more nearly symmetrical, 

 if anything, has the external side somewhat broader and marked by an 

 obscure carina defined by two faint grooves. In this specimen also, the 

 aperture appears to have been rather strongly oblique, one side project- 

 ing considerably farther than the other. 



e 



Paraparchites nickelsi var. cyclopea var. nov. 



This species is represented primarily by an extremely large specimen, 

 which agrees with P. nickelsi in most characters, except that it is very 

 much larger than any of the associated fossils referred to that species, 

 and the shell is much more coarsely pitted or punctate. The left valve 

 has the base of a well-developed spine, but the right seems to be without 

 a spine. This specimen clearly shows a small subcircular, undefined 

 muscle ( ?) spot, situated near the center of the shell. It is characterized 

 by being slightly depressed and by being smooth, without the punct^ 

 with which the rest of the surface is covered. Traces of a similar spot 

 have been observed also upon specimens referred to P. niclcelsi. 



Primitia fayettevillensis sp. nov. 



.Shell small, transverse, subquadrate. Lower margin gently convex, con- 

 verging anteriorly with the long, straight hinge line." Anterior extremity 



