GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 97 



HETEROSTEGINOIDES, new genus. 



Test generally lenticular, somewhat excentric, one side extended 

 peripherally more than the other, chambers rather coarsely per- 

 forate, embryonic chambers, often two, of nearly equal size, thick 

 Availed, chambers added as in Heterostegina, in a revolving series ex- 

 tending from the umbonal region on both sides to the periphery, 

 chambers hemispherical, the outer side strongly convex and all 

 coarsely perforate, the equatorial chambers larger than the lateral 

 •ones and nearly spherical. 



Type of the genus. — Heterosteginoides panamensis, new species. 



HETEROSTEGINOIDES PANAMENSIS, new species. 



Plate 43, figs. 1-8. 



Test biconvex, somewhat more strongly convex on one side than on 

 the other, revolving edge indistinct, surface unevenly rugose, or ir- 

 regularly pustulate, thickest in the umbonal region. Vertical section 

 showing the embryonic chambers as an equal pair of nearly spherical, 

 thick-walled chambers, equatorial chambers also nearly spherical, 

 lateral chambers hemispherical with the curved side outermost, ir- 

 regularly piled above the equatorial chambers. Horizontal section 

 showing the central chambers with the equatorial chambers arranged 

 in an irregular semi-spiral manner about them. 



Test small, between 1 and 2 millimeters in diameter. Cat. Nos. 

 324743-4, U.S.N.M. 



Occurrence. — This species was abundant in the Culebra formation 

 at station 6025, from marl, south end of Bohio Ridge switch, relo- 

 cated line, Panama Railroad, collected by Vaughan and MacDonald. 

 There are also numerous specimens at station 6011, Culebra forma- 

 tion, along east side of Gaillard Cut, collected by Vaughan and Mac- 

 Donald. It was also collected in the Culebra formation at station 

 •6024-«., Rio Agua Salud, and is doubtfully present in the Emperador 

 limestone at stations 6015 and 6016, in Empire. 



This species, which in external appearance somewhat resembles a 

 small orbitoid or nummulite, may be distinguished from most species 

 of either group hj its comparatively coarse pustulate exterior. In 

 section it can easily be recognized by its peculiar structure. 



Genus ORTHOPHRAGMINA. 



ORTHOPHRAGMINA MINIMA, new species. 



Plate 41, fig. 1. 



Test circular, very small, slightly more than 2 millimeters in 

 diameter, thickness somewhat less than half the diameter, central 

 portion very strongly umbonate, evenly rounded to a point about 



