ROTALIIDAE 187 



illustrated in Brady's figures. The most generally distributed and common form is low- 

 domed. At Sts. WS 505, 506, 507A and 507B a variety occurs in some numbers, but less 

 common than the usual type at those stations. It is characterized by the sudden increase 

 in size of the chambers of the last convolution, which accounts for more than half of the 

 total width of the shell. 



506. Eponides bradyi, sp.n. (F 367) (SG 313) (Plate VIII, figs. 36-38). 



Tnmcatulina pygmaea, Brady {no)i Hantken), 1884, FC, p. 666, pi. xcv, figs. 9, 10. 

 Ten stations: 383-7; WS 204, 205, 403, 468, 469. 



Frequent to common at all stations except St. 387, where it is very rare. All the 

 stations are in the deep water of the Drake Strait and Scotia Sea, and on both sides of 

 the convergence line. 



The organism figured by Brady under the name TnincatuUna pygmaea, Hantken, is 

 not Hantken's fossil species; the latter has a sunken umbilicus, whereas the recent form 

 has a solid convex umbilical stud. In other respects the two forms are very similar. 



Cushman (C. 1927, FWCA, p. 165, pi. v, figs. 11-13) has selected one of Brady's 

 figures (fig. 10, ut supra) as a type of his species PulvimiUnella bradyana, but the attribu- 

 tion is apparently based on the resemblance of the dorsal face of his species to Brady's 

 figure. Brady's type is in the British Museum (Natural History) and I have examined 

 it. The specimen from which fig. 10 was drawn is easily identified, but it is a sealed 

 mount and neither the specimen nor the figure exhibit the aperture, which is the vital 

 point in the separation of Eponides from Pulvimdinella. An examination of many 

 specimens from Challenger St. 5 (24° 20' N, 24° 28' W, 2740 fathoms) proves that 

 Brady's fig. 10 illustrates a young individual of the same species as his fig. 9, and that 

 both young and old specimens have the typical aperture of Eponides on the inner 

 edge of the terminal face, and not the reverted loop parallel to the peripheral edge 

 which characterizes Pulvimdinella. P. bradyana, Cushman, is therefore unrelated to the 

 organism figured by Brady, which I have renamed Eponides bradyi. The records in the 

 Falklands (F 367) and South Georgia reports (SG313) should be amended from 

 Truncatulina bradyana to Eponides bradyi. Cushman's specific name holds good for the 

 organism he described from the West coast of America. 



The description of the species is : Test thick-walled, biconvex, the convexity increasing 

 with age; dorsal side with three or more convolutions, but usually only the last con- 

 volution can be traced owing to secondary deposits of shell substance ; 7-9 chambers in 

 final convolution, sutures oblique, flush and generally indistinct; ventral side showing 

 only the chambers of the final convolution, and more distinctly than on the dorsal side; 

 sutures flush and recurved ; umbilical area filled with a solid stud of shell substance ; 

 aperture an arched slit on the inner edge of the face of the final chamber, variable in size. 



Diameter of Discovery specimens up to 0-45 mm. ; thickness 0-25 mm. It attains 

 larger proportions elsewhere. 



Eponides bradyi is essentially a deep-water species, and found in all the oceans, but 

 appears to be more frequent in the Pacific than elsewhere. 



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