96 



BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



be best understood by its analogy, in the typical condition, to a 

 broad Textularian or Bolivine shell, doubled or folded longitudinally 

 on the median line, and then rolled in the crease so formed from 

 the narrow to the broad end. The flaps of each convolution extend 

 nearly or quite to the umbilicus, and completely enclose the previous 

 whorls." 



In some species there is the tendency to uncoil as in so many other 

 genera which are close coiled. The various species appear to be 

 widely distributed. 



CASSIDULINA LiEVIGATA d'Orbigny. 



Cassidulina Ixvigata d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 282, pi. 15, 

 figs. 4, 5; Modeles, 1826, No. 41. — Williamson, Rec. Foram. Great Britain, 

 1858, p. 68, pi. 6, figs. 141, 142.— Parker and Jones, Philos. Trans., vol. 

 155, 1865, p. 377, pi. 15, figs. 1-4; pi. 17, fig. 64, a, b, c— II. B. Brady, Rep. 

 Voy. Challenger, Zoology, vol. 9, 1884, p. 428, 

 pi. 54, figs. 1-3. — H. B. Brady, Parker, and 

 Jones, Trans. Zool. Soc. London, vol. 12, 

 1888, p. 221, pi. 43, fig. 11.— Egger, Abh. 

 kon. bay. Akad. Wiss. Miinchen, CI. n, vol. 

 18, 1893, p. 302, pi. 7, figs. 47, 48, 54-56.— 

 Goes, Kongl. Svensk. Vet. Akad. Handl., 

 vol. 25, No. 9, 1894, p. 43, pi. 8, figs. 418-320.— 

 Silvestri, Mem. Pont. Accad. NuoviLincei, 

 vol. 12, 1896, p. 103, pi. 2, fig. 10.— Mil- 

 lett, Journ. Roy. Micr. Soc, 1901, p. 1. — 

 Sidebottom, Mem. Proc. Manchester Lit. 

 Philos. Soc, vol. 49, No. 5, 1905, p. 16.— 

 Pvhumbler, Zool. Jahrb., Abth. Syst., vol 

 24, 1906, p. 62. 



Description. — Nearly circular in outline, 

 lenticular or biconvex with a thin, carinate, 

 peripheral border; chambers numerous, 

 long and narrow, curved, the surface nearly 

 smooth; sutures distinct but hardly de- 

 pressed; wall calcareous, perf orate, smooth; aperture a long narrow 

 slit just below and nearly parallel to the periphery of the test; 

 color white. 



Diameter 0.50-0.90 mm. 



Distribution. — Brady records this species as occurring at three 

 stations in the North Pacific. I have material of this keeled form 

 from but one station, Albatross station D4822, in 130 fathoms, off 

 Japan. The other species are all more common in the material 

 from this region, but from the colder waters of Bering Sea as well as 

 on the northern coast of western America this species is common. 

 Rhumbler records a very small specimen measuring 0.234 mm. from 

 Chatham Island. 



Fig. 150.— Cassidulina laevigata. 



X 30. a, APERTURAL VIEW; &, 

 FRONT VIEW. 



