FOEAMIKIFERA OF THE BYRAM CALCAKEOUS MARL AT BYRAM, MISS. 



99 



Genus PTTlVINTrLINA Parker and Jones, 1862. 



Pulvinulina byramensis Cushman, n. sp. 



Plate XXII, figures 4, 5. 



Test small, biconvex, rotaliform, consisting 

 of about three coils, seven or eight chambers in 

 the last-formed coil; on the dorsal side sutures 

 oblique and at a considerable angle with the 

 periphery, somewhat limbate; on the ventral 

 side the chambers extend in to the center, 

 which is usually not umbilicate; sutures nearly 

 straight; surface polished, punctations appear- 

 incr as light tubules against the translucent wall; 

 aperture near the inner end of the chamber on 

 the ventral side, with a definite valvular lip, 

 the aperture hidden below but when examined 

 found to be composed, in the adult, of several 

 adjacent small rounded openings. Diameter 

 1.5 millimeters or less. 



This is a common species in the marl at 

 Byram. 



The features of the aperture in this species 

 are peculiar, and with its other characters it 

 seems to be well defined. 



Pulvinulina advena Cushman, n. sp. 



Plate XXII, figure 8. 



Test minute, planoconvex, composed of two 

 and a half coils, periphery deeply lobulate, 

 chambers few, elongate, broadest at the outer 

 end, six or seven in the last-formed whorl 

 periphery of the chambers somewhat tubulated, 

 remainder of surface slightly papillose on the 

 dorsal side, wliich is flat, ventral side with each 

 chamber more tumid, sutures depressed and 

 distinct, the surface granulose with coarse, 

 almost spinose projections, chambers continu- 

 ing in to the umbilicus, where they meet; 

 aperture near the periphery of the test at the 

 base of the last-formed chamber. Diameter 

 0.20 millimeter. 



This species is rare in the Byram marl. It 

 finds its nearest ally, so far as ornamentation 

 shows, in RotaJia schroeteriana Parker and Jones 

 var. inflata Millett. It has a similar surface 

 ornamentation in the spinose or granular sur- 

 face and in the fimbriated character of the 

 peripheral margins of the chambers. Tliis 

 variety, described by Millett from specimens 

 obtained in the Malay Archipelago, was found 

 again by Heron-Allen and Earland in the 

 material from the Kerimba Archipelago, off 

 the southeastern coast of Africa. 



Pulvinulina glabrata Cushman. n. sp. 



Plate XXII, figures 6, 7. 



Test biconvex, elongate, somewhat lobulate, 

 composed of about two coils, seven chambers 

 in the last-formed coil, dorsal side convex, the 

 sutures depressed, curved, chambers convex 

 between, rapidly increasing in size as added; 

 dorsal side very coarsely punctate, the sutures 

 somewhat limbate; ventral side umbilicate, sur- 

 face smooth and with very fine punctations; 

 sutures distinct, last-formed chamber with a 

 long, straight valvular lip across the whole of 

 the depressed umbilicus; aperture beneath the 

 lip. Length 0,5 millimeter. 



P. (jlahrata is rare in the marl at Byram. It 

 differs from such closely related species as 

 P. auricula, P. t^agra, and P. ohlonga in its 

 very coarsely punctate dorsal surface and the 

 shape of the test. From P. oblonga, which has 

 a somewhat similar aperture, it differs in the 

 shorter form of the test. There are a number 

 of records for P. oblonga from the Indo-Pacific 

 region, and it would be interesting to know the 

 relation of this Byram marl species to that from 

 the Indo-Pacific. 



Genus ROTAUA Lamarck, 1804. 

 Rotalia byramensis Cushman, n. sp. 



Plate XXIII. figure 1. 



Test unequally biconvex, rotaliform, in the 

 last-formed coil six or seven chambers, dorsally 

 with the chambers somewhat triangular, the 

 sutures oblique, limbate, broad, of clear shell 

 material; ventral side with a large circular 

 mass in the umbilical regi<ui, with the sutures 

 deep and ending in a depressed ring about it; 

 aperture with a somewhat valvular lip often 

 divided into several teeth; surface on the dorsal 

 side somewhat roughened, on the ventral side 

 scrobiculate near the periphery, smoother near 

 the center. Diameter 2 millimeters or less. 



Tliis species is not common in the marl at 

 BjTam. While it belongs to the Rotalia 

 heccarii group, it is much more like the tropical 

 species now living in the Indo-Pacific than those 

 of temperate regions. R. heccarii itself is used 

 as a name to cover a great variety of things, and 

 the forms now passing under that name should 

 be more critically treated if their geographic 

 and geologic distribution is to be of value. 



