FOEAMINIFERA OF THE ATLANTIC OCEAN 59 



wall smooth, polished; aperture, a narrow crescentiform slit with a 

 large, flattened, semicircular tooth. 



Length, 1 mm.; breadth, 1 mm.; thickness, 0.35 mm. 



This is a common species in shallow water both in tropical and 

 subtropical or temperate regions. In the Tropics it is very constant 

 in its characters but some of the colder water forms assigned to it do 

 not fit as well the specific characters. The tooth in side view is seen 

 to be somewhat in front of the aperture. Quinqueloculine early 

 stages are often found and there is a tendency for the chambers to 

 assume a single plane of growth. 



Variety suhlineata H. B. Brady may not really belong to this 

 species but needs further study. 



TRILOCULINA CIRCULARIS Bornemann, var. SUBLINEATA H. B. Brady 



Heron-Allen and Earland record this variety as new to the British 

 Isles from the Clare Island region of Ireland ^ in the following words: 



" Specimens found at four stations present the characteristic fea- 

 tures of this somewhat doubtful variety as figured by Brady; that 

 is, the fine costae, which in the commoner species M[iliolina] seminuda 

 Keuss, are confined to the peripheral margin of the chambers, are 

 here apparent over the whole surface of the shell." 



The other records for this variety are from the Indo-Pacific. 



TRILOCULINA GRACILIS d'Orbigny 



Plate 14, Figures 4 a~c 



Triloculina gracilis d'Orbigny, in De la Sagra, Hist. Fis. Pol. Nat. Cuba,. 

 1839, "Foraminiferes," p. 159, pi. 11, figs. 10-12.— Cushman, Publ. 311,. 

 Carnegie Instit. Washington, 1922, p. 74. 



Test elongate, slender, triloculine ; chambers rounded; sutures very 

 slightly depressed; apertural end extended into a cylindrical neck, 

 the outer end of which is enlarged and has a phialine lip; surface 

 smooth or very finely striate; aperture circular, with a slight tooth. 



Length, 0.50 mm.; breadth, 0.35 mm.; thickness, 0.10 mm. 



This species was described by d'Orbigny from shore sands of Cuba 

 and Jamaica as rare. It has occurred in material from the Tortugas 

 region. The originals of d'Orbigny suggest a slight surface ornamen- 

 tation but those that I have seen are smooth. This is a very small 

 slender species and easily overlooked. 



TRILOCULINA ROTUNDA d'Orbigny 



Plate 14, Figures 3 a-c 



Trilocxdina rotunda d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 299, No. 4. — 

 ScHLUMBERGER, M6ni. Soc. Zool. France, vol. 6, 1893, p. 206, pi. 1., figs.. 

 48-50.— Cushman, Publ. 311, Carnegie Instit. Washington, 1922, p. 73; 

 Publ. 344, 1926, p. 82. 



' Proc. Roy. Irish Acad., vol. 31, pt. 64, 1913, p. 26. 



