48 PROCEEDINGS OF THE NATIONAL MUSEUM vol.77 



appearance, but its chambers are arranged in a contraclockwise series 

 instead of a clockwise series, as in G. paalzovn. Moreover, its test has 

 the greatest breadth in the upper half, while G. yaalzowi is elongated 

 fusiform.. 



The species is named for G. M. Dawson, one of the early workers 

 on American foraminifera. 



GUTTULINA COSTULATA (Cushman) 



Plate 12, figures 3 a, 6 



Folymorphina cuspidata H. B. Brady var. costulata Cushman, U. S. Geol. 

 Survey Prof. Paper 129-F, 1922, p. 133, pi. 31, fig. 1; Prof. Paper 133, 

 1923, p. 32. 



Test elongate, fusiform., a strong spine at the base; chambers elon- 

 gated, inflated, not much embracing, arranged in a quinqueloculine 

 series, each succeeding chamber removed farther from the base; 

 sutures depressed, distinct; wall ornamented by strong, continuous, 

 bladelike costae rather widely separated from each other; aperture 

 radiate. 



Length of holotype 0.70 mm.; breadth 0.20 mm. 



The present species is one of the most clearly marked species of 

 Guttulina. In its general outline, it resembles Guttulina pulchella 

 d'Orbigny from which it is easily distinguished by its strong bladelike 

 costae entirely covering the test and a large spine at the base. 



Distribution. — Cushman reported it from the lower Oligocene, Mint 

 Spring marl. Mint Spring Bayou, Vicksburg, Miss. Specimens which 

 seem identical occur in the lower Pliocene of Beaumaris, near Mel- 

 bourne, Victoria, Australia. 



As it occurs slightly earlier in the fossil series, this may be the 

 ancestral form of Pseudopolymorphina rutila, which in its earlier stages 

 is Guttulina-like, but later becomes definitely a Pseudopolymorphina. 

 This is another of the interesting species connecting the lower Oligo- 

 cene of the United States with the late Tertiary and Recent faunas 

 of the Australian region. 



GUTTULINA SEMICOSTATA (Marsson) 



Plate 15, figures 8 a-c 



Folymorphina semicostata Marsson, Mitth. Nat. Ver. Neu-Vorpommern. u. 



Riigen, Jahrg. 10, 1878, p. 150, pi. 2, figs. 19 a-c— Franke, Abhandl. 



geol. pal. Instit. Univ. Greifswald, vol. 6, 1925, p. 78, pi. 6, fig. 21. 

 Folymorphina var. Wright, Proc. Belfast Nat. Field Club, Appendix, 



1885-86, p. 331, pi. 27, figs. 13, 14.— Jones and Chapman, Journ. 



Linn. Soc. Zool., vol. 25, 1896, p. 509, fig. 3 (in text). 



Test globular, broadest above the middle, more or less obtuse at the 

 initial end; chambers rounded, much inflated, but little embracing, 

 arranged in a quinqueloculine series, each succeeding chamber 



