320 DISCOVERY REPORTS 



37. Miliolina suborbicularis (d'Orbigny). 



Triloculina suborbicularis, d'Orbigny, 1826, TMC, p. 300, no. 12. 

 Triloculina suborbicularis, d'Orbigny, 1839, FC, p. 177, pi. x, figs. g-ii. 



Miliolina suborbicularis, Schlumberger, 1893, MGM, p. 72 (in the reprints, p. 215), text- 

 figs. 26-8; pi. ii, figs. 63, 64; pi. iii, fig. 67. 



One station: WS 215. 



A single specimen of this somewhat unsatisfactorily separated species, being the most 

 fully striate of the webbiana-fichteJiana-siiborbicularis group. (See our observations in 

 H.-A. & E. 1914 etc., FKA, 1915, p. 560.) 



The Type of d'Orbigny 's Triloculina suborbicularis could not be found, but the species 

 is identifiable from his figure, and from Schlumberger's work {ut supra). It must not be 

 confounded with d'Orbigny's Ouinqueloculiua suborbicularis (d'O. 1826, TMC, p. 302, 

 no. 29) of which we are only told that it "inhabited the Mediterranean". The 

 name has dropped into disuse, the Types, however, are in good condition in Paris, and 

 fair (though damaged) at La Rochelle. They represent a stout, broad form of M. semi- 

 nulum, the shell being quite free from striae. 



Genus Sigmoilina, Schlumberger, 1887 



38. Sigmoilina obesa, sp.n. (Plate VII, figs. 1-4). 



Twelve stations: 48, 388; WS 72, 83, 84, 86, 87, 91, 93, 108, 219, 221. 



Test free, porcellanous, broadly oval in side view with the aboral end somewhat pro- 

 jecting, elliptical in end view. Two chambers only, visible externally, the final chamber 

 occupying nearly three-quarters of the visible surface, separated by a curved sutural line 

 nearly flush with the surface of the test. The two surfaces are inequilaterally convex and 

 the peripheral edge broadly rounded. Walls thick and devoid of ornament, the surface 

 usually dull, but sometimes polished, though never to the same extent as in Sigmoilina 

 sigmoidea (Brady). Aperture, a curved slit furnished with a simple tooth. 



Both megalospheric and microspheric forms have been observed, the former as usual 

 being the most abundant. Externally there is no very great difference except in size, the 

 megalospheric form ranging up to o-8o mm. in length and 0-70 mm. in breadth as 

 compared with 1-45 mm. and 1-20 mm. for the length and breadth of the microspheric. 

 In section, the megalospheric form shows only 2-3 pairs of chambers following the 

 proloculum, while the microspheric has about 7-8 pairs. 



Sigmoilina obesa is a fairly distinctive species, its nearest ally is unquestionably 

 S. sigmoidea (Brady), but it can hardly be confused with that species externally, while, in 

 section, the sigmoid curves of the two species are quite distinctive. 



The species occurs at many stations in the Falkland area, though never in any great 

 numbers. 



39. Sigmoilina schlumberger!, Silvestri. 



Planispirina cclata, Brady, 1884, FC, p. 197, pi. viii, figs. 1-4. 



Planispirina cclata, Schlumberger, 1887, P, p. iii, text-figs. 6-7; pi. vii, figs. 12-14. 



