500 Systematic Paleontology 



Shell of moderate size, rather heavy but not very stout, whorls five or 

 six in number, regularly increasing in size, evenly but not strongly inflated, 

 obtusely shouldered posteriorly; aperture a little more than one-half and 

 body whorl a little more than three- fourths the total altitude; external 

 surface smooth excepting for incremental scratches; aperture semi-ellipti- 

 cal to ovate, the outer margin strongly arcuate, patulous anteriorly, the 

 maximum expansion a little in front of the medial line ; inner margin 

 slightly concave; umbilical pit small. 



The synonymy of this species is in a well-nigh hopeless state of con- 

 fusion. The type of the species is a cast from the Monmouth of New 

 Jersey. Weller has included under this species a series of relatively lower, 

 less inflated forms from the Matawan which seem too distant to he included 

 even within the wide limits of sex variation in outline of this group. 



This species is a much less inflated shell than either Natica obliquata 

 Hall and Meek, or Natica concinna Hall and Meek. 



Occurrence. — Monmouth Formation. Railroad cut 1 mile west of 

 Seat Pleasant, Prince George's County. 



Collections. — Maryland Geological Survey, Philadelphia Academy of 

 Natural Sciences, New Jersey Geological Survey. 



Outside Distribution. — Matawan Formation. Merchantville clay marl, 

 Wenonah sand, New Jersey. Monmouth Formation. Navesink marl, 

 New Jersey. 



Polynices (Euspira) altispira (Gabb) 



f Lunatia altispira Gabb, 1862, Proc. Acad. Nat. Sci., Phil., for 1861, p. 320. 



t Gyrodes obtusivolva Gabb, 1862, Ibidem. 



Lunatia ? altispira Meek, 1864, Check List Inv. Fossils, N. A., Cret. and 



Jur., p. 20. 

 Gyrodes ? obtusivolva Meek, 1864, Ibidem, p. 21. 

 Lunatia altispira Conrad, 1868, Cook's Geol. of New Jersey, p. 729. 

 Gyrodes obtusivolva Conrad, 1868, Ibidem. 

 Lunatia obtusivolva Conrad, 1869, Am. Jour. Conch., vol. v, p. 45, pi. i, 



fig. 11. 

 Gyrodes obtusivolva Whitfield, 1892, Mon. U. S. Geol. Survey, vol. xviii, p. 



129, pi. xvi, figs. 9-12. 

 Gyrodes altispira Johnson, 1905, Proc. Acad. Nat. Sci., Phila., p. 21. 

 Gyrodes obtusivolva Johnson, 1905, Ibidem. 

 Gyrodes altispira Weller, 1907, Geol. Survey of New Jersey, Pal., vol. iv, 



p. 687, pi. lxxvii, figs. 19-21. 



