FOEAMINIFERA OF THE ATLANTIC OCEAN 



71 



the periphery rounded; suture distinct, depressed wall smooth; aper- 

 ture generally broadly elliptical with a small flattened tooth partially 

 filling the opening. 



Length, 0.75 mm.; breadth, 0.50 mm.; thickness, 0.40 mm. 



The species is widely distributed but appears to be more at home 

 in temperate regions than in the Tropics. It has not been found in 

 the West Indian region but is known from the eastern coast of the 

 United States and from the coasts of Europe with many records 

 from the Mediterranean and Indo-Pacific. 



PYRGO DEPRESSA (d'Orbigny) 



Plate 19, Figures 4, 5 



Biloculina depressa d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 298, No. 

 7, Modules No. 91. 



There has been much confusion in regard to this and related 

 species. From a study of d'Orbigny's model, it is apparent that P. 

 depressa has a very much compressed test, with a keel entirely about 

 the periphery and with the aperture very narrow and elongate with 

 a flattened, very broad tooth nearly filling the aperture. Such speci- 

 mens are widely distributed, but, as Brady figures in the Challenger 

 report, as this species, specimens with a tubularneck and rounded aper- 

 ture with a small bifid tooth, many of the later records based on these 

 figures are doubtful without seeing the actual specimens. The typi- 

 cal form of the species is here figured from off the southwest coast of 

 Ireland. It is widely distributed but usually in cool and fairly deep 

 waters. 



The form figured by Williamson as Biloculina ringens, var. carinata^ 



is probably this species. His figures are reproduced here (pi. 19, 



fig. 5). 



Pyrgo depressa — Material examined 



PYRGO MURRHINA (Schwager) 



Plate 19, Figures 6, 7 



Biloculina murrhina Schwager, /Voyaro-Exped., Geol., vol. 2, 1866, p. 203, 

 pi. 4 figs. 15 a-c. — Munier-Chalmas and Schlumberger, Bull. Soc. G6ol. 

 France, ser. 3, vol. 13, 1885, p. 283, figs. 9, 10; p. 290, figs. 15, 16.— 



»Rec. Foram. Ot. Britain, 1858, pi. 7, fips. 172-174. 



