92 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1021. 



from the western part of the Indian Ocean, off 

 the coast of Africa. In spite of other records 

 the typical form of the species occui's mainly in 

 the Indo-Pacific region. 



Bolivina mississippiensis Cushman, n. sp. 



Plate XV, figure 5. 



Test elongate, slender, gradually tapering 

 from the subacute initial end (o tiie l)roadly 

 rounded apertural end; thickest in tlie median 

 line; chambers numerous, wider tlian high, 

 curved, sutures marked by limhate lines, 

 broadly curved and somewhat l)r(>ken near the 

 inner end, not depressed; surface of test smooth 

 and even. Length about 0.4 millimeter. 



This species is rare in the Byram marl. It 

 may be distinguished by the narrow, tapering 

 form, the peculiarly marked sutures, and the 

 very even smooth surface. 



Genus VERNETJILINA DOrbigny, 1840. 



Vcrneuilina spinulosa Reuss var. glabrata Cushman, n. 

 var. 



Test pyramidal, thiee-sided, wiliest above 

 the middle, generally triangular in transverse 

 section, the sides somewhat concave; angles of 

 the test bluntly angled or even rounded, with- 

 out spines; surface smooth; aperture small, at 

 the inner side of the last-formed chamher. 

 Length 0.75 millimeter or less. 



This variety of the species is fairly common 

 in the typical Byram marl. It thffers from the 

 typical form of the species in its lack of spines, 

 the edges often being rounded and thickened. 

 No specimens approaching tlie typical form 

 were found. 



The species is very characteristic of shallow 

 tropical and subtropical waters of the Indo- 

 Pacilic region. 



Genus CLAVTILINA DOrbigny, 1826. 

 Clavulina byramensis Cushman, n. sp. 



Plate XVI, figure 1. 



Test elongate, subcylindrical, tlie early 

 chambers triserial, forming but a small por- 

 tion of the test; later ones uniserial, both por- 

 tions rounded; sutures slightly depressed, often 

 not very distinct otherwise; aperture termi- 

 nal, central, roundest!; wall coarsely arena- 

 ceous but smoothly finished. Length 2 milli- 

 met(^rs or less. 



This form is very common in the Byram 

 marl and one of the characteristic species. 



The earlv portion is small in proportion to 

 the whole test and consists of a considerable 

 number of rounded chambers in a triserial 

 arrangement, but the resulting mass with 

 rounded angles forms a bulbous tip to the 

 otherwise tapering test. The sutui-es of this 

 early portion are usually very indistinct. 



This resembles certain tropical Pacific spe- 

 cies and probably has its affinities in that 

 region. It is cjuite likely that Pacific forms 

 which have been referred by authors to C. 

 parisieiis:is D'Orbigny are closer to this species. 



Genus VrRGULINA D'Orbigny, 1826. 



Virgulina sp. 



Plate XVI. figures 2a, 2b, 3. 



A rare species in the marl at Byram is fig- 

 ured. It is mucii compressed, the later cham- 

 bers resembling those of Bolivina in being elon- 

 gate and curved. The surface is smooth, and 

 in some of its characters this form resembles 

 r. siibsqiiamosa Egger, but it does not have 

 the curved a.xis of that species. Certain 

 specimens from the Indo-Pacific region suggest 

 this form from Byram. Some of the figures of 

 the Kerimba Archipelago material which Heron- 

 Allen and Earland'' assign to I', schreibersiana 

 Czjzek are very similar to this. They note that 

 the typical form is very rare and then say : " The 

 form generally assimied throughout the gather- 

 ings is a broad-mouthed, somewhat compressed 

 but regular-chambered type, varying greatly in 

 proportionate length and breadth." Our speci- 

 mens in certain respects resemble this form. 



Genus BULIMtNA D'Orbigny, 1826. 

 Bulimina ovata D'Orbigny? 



Plate XVI, figure 4. 



Bidhiuna ovala D'Orbigny, Foraminif^res fossilee du 

 liassin tertiaire de Vienne, p. 185. pi. 11, figs. 13, 

 14, lS4f). 

 II. 15. Brady, Chalhuijir Rept., Zcjology, \o\ 9, p. 

 400. pi. .50, figs, 13a. b, 18S4. 



This species is very rare in the Byram marl, 

 and the correctness of the identification is very 

 questionable. Tiie specimen figured is elon- 

 gate, oval, antl has a smooth surface and 

 somewhat elongate chambers with fairly de- 

 pressed sutun^s. 



sZool. Sue. Loudou Trans., vol. 20, p. 643, pi. 4y, tigs. 1-12, 1915. 



