NO. lO AMERICAN SPECIES OF LEPIDOCYCLINA VAUGHAN I3 



figures i, 2; and an external view, also X 10, of a specimen from 

 the Byram marl of Mississippi is illustrated for comparison. The 

 same species is found at the La Ceiba crossing of Rio Buena Vista. 



LEPIDOCYCLINA (LEPIDOCYCLINA) WAYLANDVAUGHANI Cole 



Plate 5, figs. 1-3, 5, 6 



1928. Lepidocyclina (LcpidocycUna) waylanch'aughani Cole, Bull. Amer. Pal., 

 vol. 14, p. 221, pi. 35, figs. l-IO. 



Cole's original description of this species is as follows : 



Test thin, waferlike without any pronounced umbo; generally flattened, but 

 occasionally slightly sellaeform ; surface smooth, occasionally obscurely reticu- 

 late, especially toward the margins ; entirely without papillae, except a few 

 very small ones which are sometimes present in the umbonal region. 



Embryonic chambers nearly equal, separated by a straight wall ; outer wall 

 moderately thick, about 0.028 mm ; greatest diameter of the embryonic chambers 

 0.53 mm, the least 0.42 mm. 



Equatorial chambers hexagonal, becoming ogival in the outer rings. 



In the vertical section, the number of lateral chambers over the center in the 

 megalospheric form, on each side of the equatorial chambers are 5 to 6, which 

 gradually decrease in number toward the periphery. Equatorial chambers very 

 small at the center, gradually increasing in size as they approach the periphery 

 until they occupy the entire thickness of the test. At the periphery, the equatorial 

 chambers are twice as high as broad. The lateral chambers are low, compressed 

 and relatively thick walled ; pillars few and weakly developed. 



Diameter of the megalospheric form 8 mm ; thickness 0.70 to 0.80 mm. 



One form of the species develops lobes to such an extent that it almost forms 

 a cross. All graduations between the perfectly round forms and the extreme 

 development of the " cross " form may be found, although the lobate forms are 

 rather scarce. 



The illustrations on plate 5 are intended to show the extreme limits 

 of variation of the species. The upper specimen of figure i has over 

 the central area papillae so small that they probably will not be visible 

 in the reproduction. In the lower specimen of the same figure the 

 papillae arc larger. In the specimen represented by figure 5 there are 

 over the central area five knoblike processes. There appear to be all 

 the intermediate stages between specimens with scattered papillae and 

 specimens in which the papillae are segregated and form knobs. 

 Figure 3 represents a vertical section, X 20, of a specimen with 

 scattered papillae; figure 6 illustrates a vertical section, X 20, of a 

 specimen with knobs. Figure 2 represents a part of a horizontal 

 section, X 20, of a specimen similar to the one represented by figure 3. 

 The hexagonal shape of the equatorial chambers is strikingly regular. 

 L. waylandvaughanl belongs in the same group of species as do L. 

 canellei Lem. and R. Douv., L. parvula Cushman, L. miraflorensis 



