78 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1919. 



neai- the center, more or less rhomboid toward 

 the periphery, with the out(>r peripheral wall 

 curved. 



So far as described material is concerned 

 this is an unusual form for American species 

 of Lepidocyclina, especially in its embryonic 

 chambers. 



Type specimen, vertical sections (U. S. N. M. 

 catalogue No. 324741). The species is fairly 

 abundant at stations 6586 e and 6587, near 

 the mouth of Tonosi River, Panama; D. F. 

 MacDonald, collector. It was also collected 

 by MacDonald at station 6512, in the river 

 bed at David, Panama. 



Lepidocyclina antillea Cushman. 



Plate XXXV, figures 4, 5. 



Lepidocyclina antiUea Cushman, Carnegie Inst. Washington 

 Pub. 291, p. 63, pi. 3, fig. 3, 1919. 



Test compressed, circular, rather evenly 

 biconvex, lenticular; central portion highest, 

 thence gradually thinning toward the periph- 

 ery; central area strongly papillate; remain- 

 der of the surface less strongly so. 



The vertical section shows equatorial cham- 

 bers increasing in height toward the periphery, 

 those of the central region measuring less than 

 0.1 millimeter, those of the periphery as much 

 as 0.5 millimeter in height; outer wall of the 

 equatorial chambers very squarely truncated. 



Lateral chambers not numerous, in the cen- 

 tral tliickened region only 6 or 7 chambers in 

 a colunm, and tliis number is gradually reduced 

 toward the periphery. Central region and 

 whole test in lesser degree marked by very 

 heavy and numerous pillars, greatest width 

 near the outer end, thence gradually tapering 

 toward the center; outer ends rounded, form- 

 ing the papillae of the surface. In the central 

 region the surface area occupied by the pillars 

 is greater than that taken up by the lateral 

 chambers. 



In horizontal section, or at least in the some- 

 what broadly oblique section, the equatorial 

 chambers are of the curved Lepidocyclinu form 

 instead of the more typical hexagonal shape. 



Diameter of test averages about 5 millime- 

 ters. 



The type locality for this species is U. S. 

 G. S. station 6897, conglomerate and sand- 

 stone below upper limestone bed, Anse Ecaille 

 side of point between Anse EcaiUe and Anse 



Lezard, St. Bartholomew; T. W. Vaughan, 

 collector. Material apparently weathered out 

 from the matrix is abundant here and also at 

 station 6897 b, point between Colombier Point 

 and bay next to St. Jean Bay, St. Bartholo- 

 mew; T. W. Vaughan, collector. Hand speci- 

 mens showing sections of this heavy-pillared 

 species were abundant in a hard, cherty mate- 

 rial at stations 6902, in the southeast section 

 of the southwest side of the island near Negre 

 Point, St. Bartholomew, at an elevation of 360 

 feet, and 6903, N. 67° E. from summit of Negre 

 Point across low saddleback of point, at an 

 altitude of 220 feet. 



This species is related in many ways to 

 Lepidocyclina inacdonaldi Cushman, from the 

 white limestone at David, Panama. The gen- 

 eral vertical section is much more heavily pil- 

 lared in L. antiUea, although the figure, not 

 being exactly central, shows this much less 

 strongly than many of the weathered sections 

 in hand specimens. The material from the 

 white limestone at David, Panama (U. S. G. S. 

 station 6512), referred to as L. panamensis, 

 may belong to L. antiUea, and also the sections 

 resembUng L. macdonaldi. 



Lepidocyclina dupUcata Cushman. 



Plate XXXV, figures 1-3. 



Lepidocyclina duplicafa Cushman, U. S. Nat. Mus. Bull. 

 103, p. 96, pi. 41, figs. 2-1, 1918. 



Test of medium size, 10 to 14 millimeters 

 in diameter, very much thickened in the um- 

 bonal region, usually the thickness about one- 

 half the diameter, central portion without the 

 flattened periphery, subspherical, thinning rap- 

 idly toward the periphery, then thickening 

 again at the margin, which is doubly plicate 

 in some of the best-preserved specimens. Sur- 

 face of the umbonal portion studded with 

 numerous fine papdlae marking the surface 

 terminations of the pillars; peripheral portion 

 nearly smooth. 



Tlie vertical section shows the enabryonic 

 chambers as very small, apparently micro- 

 spheric in the specimens sectioned, appearing 

 spiral, as is usual in the microspheric form. 

 Lateral chambers numerous, flattened or len- 

 tictdar, the numerous pillars as mde as or 

 wider than the intermediate columns of cham- 

 bers, especially in the central portion; rapidly 

 increasing in size toward the surface. Equa- 



