60 



SHORTER (CONTRIBUTIONS TO GENERAL GEOLOGY, 1919. 



433L Two miles above Byi'am, on Pearl River, Miss.; 

 ledge about middle of the formation; A. F. Crider, 

 collector. 



6548. Marianna limestone, rock quarry 4 miles east of 

 Brandon, Rankin County, Miss., south of Rankin on 

 Alabama & Vicksburg Railway; T. W. Vaughan, collector. 



6644. Marianna limestone, Goodwater Creek, 3 miles 

 southeast of Vossburg, Miss.; C. W. Cooke, collector. 



6645. Marianna limestone, roadside on hill in sec. 2, 

 IJ miles south-southeast of Heidelberg, Jasper County, 

 Miss.; beds 1-5 of section; C. W. Cooke, collector. 



6767. Marianna limestone, west side of Marianna, Fla. 



Lepidocyclina hilli Cushman, n. sp. 



Plate XV, figure 1 ; Plate XVI, figure 2. 



Test circular, flat, thin; central portion 

 elevated slightly more on one side than on the 

 other; gradually sloping from the thickened 

 center to the peripheral portion, which is flat; 

 umhonal region in the very center strongly 

 papillate, with a few large papillae about 

 which may be as many as eight of the lateral 

 chambers, forming a concentric series of 

 reticulations; papillae smaller as the distance 

 from the center of the test increases. 



A vertical section near the edge shows the 

 equatorial chambers about three times as 

 high as broad; lateral chambers numerous, 

 very low and broad, in vertical columns. 



Type specimen (U. S. N. M. No. 135220) 

 from the Guallava sandstone of Costa Rica, 

 collected by R. T. Hill. Specimens from 

 U. S. G. S. station 6722 (Ocala hmestone, old 

 quarry three-fourths mile west and three-fourths 

 mile north from Monroeville, Ala.), collected 

 by C. W. Cooke, seem to be close to this species. 



In its general form L. Mlli strongly resembles 

 L. mantelli (Morton), but the slope from the 

 central umbo is carried out over a wider area 

 and the large papillae of the center with the 

 smaller ones over a large part of the surface 

 win at once distinguish it from that species. 

 The umhonal region with the depressed con- 

 centric series of reticulations about the large 

 papillae suggests L. rnorgani, which is in other 

 respects very different. 



Lepidocyclina undulata Cushman. 



Plate XV, figures 2-5. 



Lepidocyclina undulata Cushman, Carnegie Inst. Wash- 

 ington Pub. 291, p. 65, pi. 3, figs, la, 2, 8, 9; pi. 15. 

 fig. 5, 1919. 



Test large, slightly papillate, lenticular; the 

 umbonate region scarcely if at all raised ; whole 



test undulate or saddle-shaped, often ])cnt 

 nearly double. 



Vertical sections (PI. XV, fig. 4) of tliis 

 species show pUlars very constant but of small 

 diameter scattered throughout the central 

 half of the test and a few toward the peripheral 

 portion; equatorial chambers fairly high and 

 with a series of 6 to 8 rather large perforations 

 in the peripheral wall; lateral chambers thick- 

 walled and rather large, comparatively few, 

 usually not more than six in a vertical column. 



Equatorial chambers (PI. XV, figs. 2, 3) 

 hexagonal in horizontal section. 



Diameter in the largest specimens apparently 

 exceeding 100 millimeters when complete. 



The type locality for this species is U. S. 

 G. S. station 6863, High Point, Antigua, 

 Leeward Islands; collected by T. W. Vaughan. 

 Specimens were abundant at this station. 

 Other material from Antigua apparently re- 

 ferable to this species was obtained at stations 

 6858, Wetherell Point; 6874, Blizzards Mill; 

 (?) 6880, west side of Otto's estate, west 

 side of Golden Grove road; 6881, bluff on 

 north side of Willoughby Bay; and 6942, 

 boulders on south side of Monks HiU, Falmouth. 



This seems to be the largest known species 

 of Lepidocyclina, being larger than L. eleiphan- 

 tina. The material here figured froin station 

 6881 (PI. X\", fig. 5) is for the most part com- 

 posed of smaller specimens which may possibly 

 belong to another species but which have the 

 sadcUe-shaped form of the larger specimens. 

 The specimens make up a large proportion of 

 the mass of the rock. 



Lepidocyclina georgiana Cushman, n. sp. 



Plate XVI, figure 1; Plate XVII, figures 1-3; Plate 

 XVIII, figures 1, 2. 



Test large, flattened, or slightly undulate 

 or sellaeform; largest specimens measuring 

 70 millimeters in diameter, more general run 

 of specimens 25 to 50 millimeters; central 

 region in young and medium-sized specimens 

 prominently umbonate, in the largest ones 

 much less so ; surface in the earlier stages scro- 

 biculate toward the margins, becoming rather 

 strongly papillate toward the center and espe- 

 cially on the umhonal region; umbo small, 

 usually less than 5 millimeters in diameter. 



The horizontal section (PI. XVIII, fig. 1) 

 shows the chambers of the equatorial band 



