94 



SHOKTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1921. 



Specimens that seem identical with this 

 species are common in the Bjram marl. They 

 have usually not more than three chambers. 

 The earliest one, the proloculum before the 

 later chambers are added, is very similar to 

 Lagena glohosa in form and could easily be 

 mistaken for it, even the aperture not having 

 clearly developed its radiate character at this 

 stage. Specimens that would be classed as 

 L. glohosa are found in the Byram marl, but 

 with them are specimens in the two and three 

 chambered stages, showing that they are the 

 young of Poh/morphina gibba. 



This is a widely distributed species, both in 

 recent seas and in the fossil series. I have 

 already recorded it from the Pliocene and 

 Miocene of the Coastal Plain. 



Polymorphina gibba D'Orbigny, fistulose form. 



Plate XVIII, figures 3a, 3b. 



The figured specmien shows a fistulose form 

 which may l)e referred to P. gibba. It has 

 numerous branched, semicylindrical processes, 

 mostly from the last-formed chamber. 



Polymorphina regina H. B. Brady, Parker, and Jones. 



Plate XVIII, figure 4. 



Polymorphina regina H. B. Brady, Parker, and Jones, lin- 



nean Soc London Trans., vol. 27, p. 241, pi. 41, figs. 



32a, b, 1870. 

 H. B. Brady, Challenger Kept., Zoology, vol. 9, p. 



571, pi. 73," figs. 11-13, 1884. 

 Egger, K. bayer. .\kad. Wiss. Miinchen Abb., CI. 2, 



vol. 18, p. 310, pi. 9, figs. 45, 50, 51, 1893. 

 Millett, Roy. Micr. Soc. Jour., p. 265, 1903. 

 Bagg, Maryland Geol. Survey, Miocene, p. 478, pi. 



133, fig. 7, 1904; U. S. Nat. Mus. Proc, vol. 34, p. 



149, mos. 



Chapman, Quekett Micr. (Uub Jour., 2d ser., vol. 10. 



p. 132, pi. 10, fig. 4, 1907 [1909]; Roy. Soc. Victoria 



Proc. vol. 22, p. 281, 1910. 

 Cushman, U. S. Nat. Mus. Bull. 71, pt. 3, p. 91, pi. 



41, figs. 6, 7, 1913; U. S. Geol. Survey Bull. 676, p. 



.54, pi. 11, figs. 3, 4, 1918. 

 Heron-Allen and Earland. Zool. Soc. London Trans.. 



vol. 20, p. 673, 1915. 



Test elongate, fusiform; chambers tumid, 

 distinct, especially in the later portion, sutures 

 deep; wall ornamented by numerous longi- 

 tudinal costae, usually continuing unbroken 

 across several chambers; aperture radiate, 

 somewhat produced. Length 1 millimeter or 

 less. 



This species is rare in the Byram marl. It is 

 known from the Miocene of the Coastal Plain in 



the Calvert formation of Chesapeake Beach, 

 Md. (Bagg), and the Duplin marl of Mayesville, 

 S. C. (Cushman). It is not known to occur in 

 the Tertiary of Europe but is a typical species 

 in the shallow water of the tropical and sub- 

 tropical Pacific and Indian oceans. 



This is another of the species by which the 

 foraminiferal fauna of the Byram marl is cor- 

 related with the living fauna of the Indo- 

 Pacific. 



The specimen here figured is a young' one 

 with but a few chambers developed, not show- 

 ing the typical adult form. 



Polymorphina byramensis Cushman, n. sp. 



Plate XVII, figures 2a, 2b. 



Test short and broad, triangular, composed 

 of a few chambers, usually only four, all except 

 a final fifth chamber extending back to the base 

 of the proloculum, forming a truncate test; 

 chambers inflated, sutures deep and distinct; 

 surface smooth; aperture radiate, only slightly 

 produced. Length 0.75 millimeter or less. 



This is one of the most common species in the 

 Byram marl. It is characterized by its trun- 

 cate base and triangular form. It resembles 

 the group of Polymorph Ina represented by P. 

 trigoniila Reuss. Sidebottom * has figured a 

 specimen which he refers to P. lactea but states 

 that it is not typical. It is near this species. 



The proloculum alone strongly resembles that 

 of P. gibba in being spherical and translucent. 

 Most of the specimens have the three or four 

 chambers with the triangular, truncate test, 

 but a few have a fifth chamber, usually smaller 

 than the rest and near the upper part of the 

 test. This seems to mark the full development 

 of the species. 



Polymorphina problema D'Orbigny? 



Plate XVIII, figure 1. 



Polymorphina (Guttxdina) problema D'Orbigny, Annates 



sci. nat.. vol. 7, p. 266, No. 14, Modeles, No. 61, 



1826. 

 Gultulina problema D'Orbigny, Foraminif^res fossiles du 



bassin tertiaire de Vienne, p. 224, pi. 12, figs. 26-28, 



1846. 



The form of Polymorphina problema found in 

 the Byram marl is not unlike that figured by 

 Brady '' but is even more like recent specimens 



< Manchester Lit. and Philos. Soc. Mem. and Proc., vol. 51, No. 9, 

 p. 9, pi. 2, fig. n, 1907. 

 5 ChttUenger Kept., Zoology, vol. 9, p. 56», pi. 72, fig. 20; pi. 73, flg. 1, 



ISM. 



