98 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



two-thirds of the distance from the center to the periphery, from 

 which point to the periphery the surface is nearly flat; surface of 

 the test comparatively smooth. 



Horizontal section through the equatorial chambers shows very 

 fine rectangular chambers and the embryonic chambers nearly equal 

 in size. 



Vertical section (fig. 1) shows well the contour of the test in this 

 section, the strongly curved central umbonate portion making up 

 two-thirds or more of the width and the peripheral flange with its 

 nearly parallel sides. The chambers are very small, except the 

 embryonic central chambers, which are nearly equal and have a 

 straight division line between them. The lateral chambers are in 

 vertical columns, but the test is without pillars. In the central region 

 there may be more than 20 chambers in a vertical column, and even 

 on the peripheral flange there are usually three or four in a column 

 on each side of the equatorial chambers. 



Occurrence. — Type-specimen — the vertical section here figured. 

 Collection of the U. S. National Museum Catalogue No. 324745. 



The species is abundant at United States Geological Survey sta- 

 tion 6512 in the white limestone, in the river bed above the ice plant 

 near David, Panama, collected by D. F. MacDonald. 



This is a very small species yet it has an abundance of very fine 

 chambers. There is an exceptional development of lateral chambers 

 in the region of the periphery. 



Genus NUMMULITES. 



NUMMULITES PANAMENSIS, new species. 



Plate 43, figs. 9, 10. 



Test small, about 14 millimeters in diameter, much compressed, 

 chambers very numerous, about 22 in the last formed coil, each *in 

 section two to three times as high as long, test of about four whorls, 

 walls comparatively thick, whole test lenticular, peripheral margin 

 broadly rounded, central portion nearly flat. 



Occurrence. — Specimens occur with some frequency in the Culebra 

 formation at station 6025, in marl, south end of Bohio Ridge switch, 

 relocated line, Panama Railroad, collected by Vaughan and Mac- 

 Donald. Type-specimen, U. S. National Museum Catalogue No. 

 324746. The species was also collected in the Culebra formation at 

 station 6024-#, Rio Agua Salud, and doubtfully at station 6026, 2 

 miles south of Monte Lirio, on the relocated line of the Panama 

 Railroad. 



NUMMULITES DAVIDENSIS, new species. 



Plate 43, fig. 11. 



Test comparatively small, about 3^ millimeters in diameter, some- 

 what compressed, chambers about twice as high as long in median 



