58 BULLETIN 104, UNITED STATES NATIONAL MUSEUM 



Turbinulina d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 275 (genotype, by 

 designation, Rotalia (Turhinulhia) beccarii {'Lmnsieus)=^ Nautilus beccarii 

 Linnaeus) . 



Rosalina (part) of Authors. 



Truncalulina (part) of Authors. 



Genoholotype. — Rotalia trochidiformis Lamarck. 



Test trochoid, usually biconvex, the umbilical area closed, usually 

 having a conical plug of clear shell material; sutures on the ventral 

 side usually deeply depressed and often ornamented along the sides, 

 dorsal side usually limbate; wall calcareous, perforate, often double; 

 aperture, an arched opening at the border of the ventral face midway 

 between the periphery and the umbilical area, interseptal canals 

 sometimes present. 



Cretaceous to Recent. 



As restricted by the above description, Rotalia in the Atlantic is 

 represented by a very few species. 



ROTALIA BECCARH (Linnaeus) 



Plate 12, figures 1-7; plate 13, figures 1, 2 



"Cornu Hammonis" Plancus, Conch. Min., 1739, p. 8, pi. 1, fig. 1. 

 "Ammonia unita" Gualtieri, Index Test., 1742, pi. 19, figs. H, I. 

 Nautilus beccarii Linnaeus, Syst. Nat., ed. 12, 1767, p. 1162; ed. 13 (Gme- 



lin's) 1788, p. 3370. 

 Streblus beccarii Fischer, Advers. ZooL, fasc. 2, 1819, p. 75. 

 Rotalia (Turbinulina) beccarii d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 275 



No. 42; Modeles, No. 74. 

 Discorbula ariminensis Lamarck, Tabl. Encycl. et Meth., 1816, pi. 466, figs. 



6 a, b. 

 Rotalina beccarii Williamson, Rec. Foram. Gt. Britain, 1858, p. 48, pi. 4, 



figs. 90-92. 



In ''Contributions from the Cushman Laboratory for Foraminif- 

 eral Research," ^^ I have given an account of this species and a dis- 

 cussion of the various stages of its development which is given below. 



Brady in the Challenger Report (pp. 704-705) gives the follomng 

 very excellent description: "Rotalia beccarii, the central species of 

 the genus from a morphological point of view, and by far the best 

 known, is not well represented in the Challenger collections. 



"In its typical presentment the test forms a depressed turbinoid 

 spire, the two faces of which are nearly equally convex, and the pe- 

 ripheral edge rounded and more or less lobulated. The segments, 

 which are numerous and a httle inflated, are arranged in three to 

 four convolutions; on the superior side the sutures are flush or very 

 slightly depressed, and marked by the broad lines of the thick clear 

 septa within; whilst on the inferior they are irregularly excavated, 

 and their borders, as well as the umbilical portion of the surface, are 



2* Vol. 4, 1928, pp. 103-107, pi. 16, flgs. 1-7. 



