40 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1919. 



Culebra formation: 



Lopidocyclina canellci Lomoino and R. Douvill^. 

 pauameiisis C'ushinan? 

 chapori Lemoine and R. Douville. 

 Tonosi, Panama (in beds of the age of the Culebra forma- 

 tion) : 



Lepidocyclina panamensis Cushman. 

 duplicata Cushman. 

 Emperador limestone: 



Lepidocyclina vaughani Cushman. 

 panamensis Cushman? 

 Cuba: 



Lepidocyclina schlumbergeri Lemoine and R. Dou- 

 \dlle. 

 marginata (Michelotti). 

 kempi (O'Connell). 

 morgani Lemoine and R. Dou\'ill6. 

 crassata Cushman. 



canellei var. yurnagunensis Cushman. 

 sumatrensis (Brady). 

 San Rafael formation, Mexico: 



Lepidocyclina gigas var. mexicana Cushman, n. var. 



AMERICAN SPECIES OF ORTHOPHRAGMINA. 



The genus Orthophragmina includes those 

 species of orbitoicl Forammifera in which the 

 chambers of the equatorial band are rectangu- 

 lar. Many of the species are stellate, with 

 produced angles, or, if circular, have a stellate, 

 raised ornamentation. Others, however, have 

 the chcular form with various!}^ ornamented 

 surfaces. The genus so far as known in America 

 and Europe seems to be limited to the forma- 

 tions of Eocene age, and in America at least 

 it is largely confined to the upper Eocene. 



The structure of the test of Orthophragmina 

 is essentially the same as that of Lepidocydina, 

 which is diagrammaticaUy figured on page 56. 

 An equatorial band of chambere, which are 

 rectangular in horizontal section, occupies the 

 middle portion. At either side are the lateral 

 chambers, usually polygonal in outline, and 

 placed one above another in vertical columns. 

 These columns are here and there separated by 

 the piUars, masses of compact shelly material 

 arising from the wall of the equatorial chambers 

 and thence extending to the surface. The 

 pillars are especially developed in the thicker 

 central region and increase in diameter toward 

 the surface, where they usually api:)ear as 

 rounded knobs or pustules extending a slight 

 distance above the general surface of the test. 

 Their fxmction seems to be to give strength to 

 the thickened portion of the test. 



The lateral chambers and in many species 

 the equatorial chambers also average much 

 smaller than those of most species of Lepido- 



cyclina. In vertical section the lateral cham- 

 bers of Orthophragmina, where they are not 

 separated by piUars, have a zigzag Ime between 

 adjacent columns, and usually this line serves 

 when once seen to distinguish the genus in 

 rock sections. 



Very little has been known of the American 

 species except references to them in papers by 

 H. Douville. In 1917 I described several 

 species from the Ocala limestone of Georgia 

 and Florida.' Those species are included in 

 the present paper with additional records for 

 their distribution. .Uso the material from 

 Cuba, St. Bartholomew, Panama, Nicaragua, 

 and California has been added, so that the 17 

 species and varieties here described cover a 

 wide region. There are many other species, 

 but they are not represented by identifiable 

 material. In southern Europe, especially in 

 France and Italy, as many as 10 or 12 species 

 are listed from single localities, showing that 

 in aU probability the number of American 

 species will be greatly increased in future work. 

 This ])aper should therefore be looked upon as 

 only a pioneer attempt at making a basis on 

 which a larger study of the American species 

 can be built.^ 



Orthophragmina cubensis Cushman. 



Plate Vri, figures 1, 2. 



Orthophragmina cubensis Cushman, Carnegie Inst. Wash- 

 ington Pub. 291, p. 52, pi. 9, fig. 3; pi. 10, figs. 2-4, 

 1919. 



Test sniall, lenticular, comparatively thick; 

 thickness in the center greatest, about three- 

 fifths the diameter; circular, gradually thin- 

 ning toward the periphery l)ut without a defi- 

 nite border; periphery rounded; surface with 

 numerous rather large papillae in the center, 

 gradually smaller toward the periphery. 



In vertical section the test, owing to the 

 straightness of the slope from center to periph- 

 ery, is almost diamond shaped; jiillars of the 

 center very heavy, thick, increasmg rapidly in 

 diameter toward tlie surface, the peripheral 

 ends projectmg above the adjacent lateral 

 chambers; equatorial chambers of the same 

 height, the band hardly increasing in diameter 

 from center to periphery, very small; lateral 



lU. S. Geol. Survey Prof. Paper 108, pp. 115-124; pis. 40-44, 1917. 



2 A species of OrfhnphTagmina recognized after this paper was in type 

 is described in a manuscript now awaiting publication in Prof. Paper 

 128. 



