454 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



rather rare, being found at but four stations. The correlation of 

 apertural characters and form of test with rounded angles is very- 

 constant. 



Triloculina advena — Material examined. 



TRILOCULINA TRICARINATA d'OrWgny. 



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

 H. B. Brady, Trana. Linn. Soc. London, vol. 24, 1864, p. 446, pi. 48, fig. 3.— 

 CusHMAN, Bull. 71, U. S. Nat. Mua., pt. 6, 1917, p. 66, pi. 25, figs. 1, 2. 



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

 p. 165, pi. 3, fig. 17a, h. — SiDEBOTTOM, Journ. Roy. Micr. Soc, 1918, p, 7. 



This species is typical and very common in the area. There are 

 two distinct varities, one elongate and very rare, and the other 



Fl03. 35, 36.— TEttOCUUNA TRICARINATA, D'ORBIGNY. 35, APERTUBAL 

 VIEW or BROAD, PECULIARLY SHAPED SPECIMEN. X 65. FROM ALBA- 

 TROSS STATION D5160. 36, APERTURAL VIEW OF A MUCH LARGER SPECT- 

 MEN WHERE THE OUTER FACE HAS A DOUBLE ANGLE. X 35. FrOM 



Albatross station d5236. 



shorter and very common. The sides are usually concave in the 

 larger species and the aperture often cruciform. In th© young there 

 are two types of aperture — one slightly prolonged, rounded, with a 

 single or usually bifid tooth, and more elongated form of test; the 

 shorter test with the aperture flush with the surface and with no 

 neck. The short variety, with rotund inflated sides but sharp 

 keeled, may be known as var. convexa, new variety. 



The records for the region include 50 stations, ranging in depth 

 from 10 to 901 fathoms (18 to 1,648 meters), the average depth 

 being 231 fathoms (423 meters). Bottom temperatures are given 



