56 BULLETIN" 10 4, UNITED STATES NATIONAL MUSEUM 



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. 



SPECIES WITH SMOOTH EXTERIOR 



TRILOCULINA TRIGONULA (Lamarck) 



Plate 12, Figures 10, 11; Plate 13, Figures 1, 2 



Miliola trigonula Lamarck, Ann. Mus., vol. 5, 1804, p. 351, No. 3, vol. 9, 



1807, pi. 17, fig. 4. 

 Triloculina trigonula d'Orbigny, Ann. Sci. Nat., vol. 7, 1858, p. 299, No. 1, 



pi. 16, figs. 5-9; Modeles 1826, No. 93. 

 Miliolina trigonula Williamson, Rec. Foram. Gt. Britain, 1858, p. 84, pi. 7, 



figs. 180-182.— H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, 



p. 164, pi. 3, figs. 14-16. 



Test in the adult with three visible chambers, the angles rounded, 

 the periphery broadly convex, whole test somewhat longer than wide, 

 in end view rounded triangular, the sides convex; sutures distinct; 

 wall smooth; aperture with a rather broad bifid tooth. 



Length, 1 mm: breadth, 0.65-0.85 mm. 



There are very many records for this species, but it is very 

 doubtful if even a large proportion of them should be placed here. 

 Lamarck's type is from the Eocene of the Paris Basin and is a well- 

 defined species different from much of the recent material of similar 

 form. A study of sections should be made before the full characters 

 of the many similar forms can be known in detail. 



triloculina TRICARINATA d'Orbigny 



Plate 13, Figures 3 a-c 



Triloculina tricarinata d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 299, No. 7; 



Modeles, 1826, No. 94. — H. B. Brady, Trans. Linn. Soc. London, vol. 24, 



1864, p. 446, pi. 48, fig. 3. 

 Miliolina tricarinata H. B. Brady, Rep. Voy. Challenger, Zoology, vol. 9, 1884, 



p. 165, pi. 3, figs. 17 a, b. 



Test in the adult with three visible chambers, the angles of the 

 chambers sharply angled often almost carinate, whole test usually 

 somewhat longer than wide, in end view triangular, the sides straight; 

 sutures distinct; wall smooth, often polished; aperture with a narrow 

 bifid tooth or variously angled in large specimens. 



Length up to 2 millimeters. 



This is another species that needs monographic study with abun- 

 dant material, both fossil and recent and many sections. There are 

 evidently several species included under this name, but only careful 

 study of sectioned specimens especially of the microspheric form will 



