70 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1919. 



with lobes at one side or elongated oval; thick- 

 est in the central region ])ut not distinctly uni- 

 bonate, gradually decreasing in thickness to the 

 periphery; surface apparently smooth but with 

 slight enlargement becoming papillate, the 

 papillae, which are the ends of the pillars 

 rounded and projecting above the general sur- 

 face slightly, or where the test is eroded ho- 

 coming more prominent. Diameter as much 

 as 18 millimeters in adult specimens; thickness 

 about 2 millimeters. 



The horizontal section shows the chambers 

 of the equatorial band to be irregularly hexag- 

 onal, the chambers with thick walls, the annuli 

 irregular, occasionally much crowded, the 

 chambers then compressed and elongate oval; 

 embryonic chambers not seen. 



The vertical section shows the equatorial 

 band to be unusually thin, increasing some- 

 what in thickness toward the periphery, where 

 the height of the chambers is 2 to 2J times the 

 radial width; lateral chambers numerous, 10 to 

 12 in a column in the thickest portion of the 

 test, thence decreasing gradually in number 

 toward the periphery; chambers very much 

 compressed, 6 to 8 times as wide as high, ellip- 

 tical, the walls thick, usually much thicker 

 than the chamber itself; pillars very numerous, 

 increasing rapidly in diameter toward the sur- 

 face, most numerous in the thicker central por- 

 tion but in lesser numbers scattered over the 

 surface well toward the periphery. 



Conrad describes this species from the upper 

 bed at Vicksburg (hence probably the specific 

 name supera) in the following words: 



Smaller than tlie preceding [L. viantelli\ and compara- 

 tively thicker without the raised central point. Diameter 

 thirteen-twentieths of an inch. This species is readily 

 distinguished by the convex center and is limited to the 

 Oligocene strata. 



L. supera seems to be a characteristic species 

 of the upper part of the lower Oligocene, now 

 known as the BjTam calcareous marl. It has 

 been found at the following stations in Missis- 

 sippi : 



259. Vicksburg. 



2664. Vicksburg; C. W. Johnson, colJector. 



3722. Vicksburg, bluff just above the second sawmill on 

 the river, horizon No. 2 from the top; T. W. Vaughan, 

 collector. 



3729. Top of bluff opposite second sawmill, Vicksburg; 

 T. W. Vaughan, collector. 



5623. West bank of Pearl River, Byram, Hinds County; 

 G. C. Mateon, collector. 



6449. Upper fossiliferous zone. Confederate Avenue, 

 600 to 700 feet north of the bridge over Glass Bayou, Vicks- 

 burg; C. W. Cooke, collector. 



6454. Pearl River just aVxivc bridge at Byram; C. W. 

 Cooke, collector. 



6458. Rock quarry 4 miles east of 7'>randon, south of 

 Rankin, on Alabama & Vicksburg Railway, Rankin 

 County; T. W. Vaughan, collector. 



6648. Chickasawhay Ri^'er at wagon bridge a quarter of 

 a mile west of Woodward and 2 miles northwest of Waynes- 

 boro (^ounty; C. W. Cooke, collector. 



The following localities in Alabama seem to 

 have this species: . 



3646. Salt Mountain, Clarke County, near the top of (he 

 series; T. W. Vaughan, collector. 



3648. Salt Mountain, near top of the hill ; T. W. Vaughan, 

 collector. 



H. DouvUle ' has recorded L. supera from 

 Vicksburg and Byram, Miss., from a locality 

 southeast of Claiborne on Conecuh River, Ala., 

 and from Bainbridge, Ga. I have had much 

 material from Bambridge but have had no 

 material that seemed to fit this species. The 

 embryonic chambers of a specimen from Bain- 

 bridge, figured by Douville, are very thick 

 walled and seem much more like some of the 

 Ocala species. Douville gives L. supera as oc- 

 curring in the "upper Ja,ckson-Zeuglodon bed." 



The species there that is superficially like L. 

 supera in some respects is that here described 

 as L. mortoni. 



So far as the material I have had shows, L. 

 supera is confined to the Byram marl and for- 

 mations of equivalent age. 



Lepidocyclina mortoni Cushman, n. sp. 



Plate XXVII, figures 1-4; Plate XXVIII, figures 1, 2. 



Test flattened, usually somewhat sellaeform, 

 thin; central portion thickest but not umbo- 

 nate; surface very finely papillate throughout, 

 the papillae most numerous in the central por- 

 tion. Diameter as much as 20 millimeters; 

 thickness slightly more than 1 millimeter. 



The horizontal section shows the chambers 

 of the equatorial band hexagonal in general, 

 but the peripheral portion more commonly a 

 convex curve instead of a sharp angle; embry- 

 onic chambers subequal in the megalospheric 

 form, thick-walled. 



The vertical section shows the chambers of 

 the equatorial band very low, in the center 

 slightly wider than the height but toward the 

 periphery slightly larger and slightly higher 



iCompt. Rend., 1918, pp. 264, 265. 



