50 BULLETIN 161, UNITED STATES NATIONAL MUSEUM 



curved, enlarging toward the base, free from agglutinated material, 

 the lip very thin, everted, either smooth or with very slight traces of 

 teeth. Length, 0.8 mm. ; diameter, 0.45 mm. 



Holotype.—V.S.'NM. No. 22088, from Albatross Station H3898, 

 one-third mile east of northwest point Hikueru Atoll, Paumotus. 



Our figured specimen seems to be almost exactly identical with 

 that figured by Chapman from the lagoon at Funafuti. 



Genus TRILOCULINA d'Orbigny, 1826 



TrUooulina d'Orbigny, Ann. Sci. Nat., vol. 7, p. 299, 1826. — Cushman, Cushman 

 Lab. Foram. Res. Spec. Publ. No. 1, p. 151, 1928 ; U. S. Nat. Mus. Bull. 104, 

 pt. 6, p. 55, 1929. 



Miliola (part) Lamarck, Ann. Mus. d'Hist. Nat., vol. 5, p. 351, 1804. 



Miliolina (part) Williamson, Rec. Foram. Great Britain, p. 83, 1858 (and later 

 authors). 



Genotype. — By designation, Miliola trigonula Lamarck. 



Test with the early chambers quinqueloculine, at least in the micro- 

 spheric form, later ones added in the planes 120° from one another, 

 the third of each series added in the plane of the third preceding and 

 covering it so that the surface of the test is composed of but three 

 visible chambers, interior not labyrinthic ; aperture simple, typically 

 with a bifid tooth. 



This genus is definitely derived from Quinqueloculina by the addi- 

 tion of chambers 120° apart and three making up a complete cycle, 

 and the aperture typically with a bifid tooth. In the microspheric 

 form all the stages are usually present, but in the megalospheric 

 form the early quinqueloculine stages may be entirely skipped and 

 the triloculine stage taken on at once. 



In this genus there is a considerable degree of difference in the 

 characters of the aperture. Some of the species have a large semi- 

 circular aperture with a flattened tooth, which nearly fills the aper- 

 ture, while other forms have a narrow aperture with a very narrow 

 tooth typically bifid at the tip. So far as has been noted these two 

 forms are not closely related, but they need further study. In the 

 young stages of the microspheric form chambers are arranged in a 

 quinqueloculine manner, and such specimens can only be determined 

 as the young of Trilocul'tna by comparison with the adult form that 

 accompanies them. 



TRILOCULINA OBLONGA (Montagu) 



Plate 11, Figures 10 a-c 



Vermiculum oblongum Montagu, Test. Brit., p. 522, pi. 14, fig. 9, 1803. 



Triloculina oblonga d'Orbigny, Ann. Sci. Nat., vol. 7, p. 300, No. 16, 1826 ; 

 Modeles, No. 95 ; in De la Sagra, Hist. Fis. Pol. Nat. Cuba, " Forami- 

 niferes," p. 175, pi. 10, figs. 3-5, 1839.— H. B. Brady, Trans. Linn. Soc. Zool., 



