734 
THE VOYAGE OF H.M.S. CHALLENGES. 
Polystomella minima, Seguenza, 1879, Atti E. Accad. dei Lincei, ser. 3, vol. vi. p. 333, pi. xvii. 
fig. 38. 
„ striatopunctata , Terrigi, 1880, Atti dell’ Accad. Pontiff ann. xxxiii. p. 216, pi. iv. 
figs. 73, 74. 
„ antonina , Terquem, 1882, Mem. Soc. geol. France, ser. 3, vol. ii. p. 47, pi. ii. 
fig. 25, a. b. 
This is one of the weaker modifications in which the distinctively Polystomelline 
characters are only partially recognisable. The test is discoidal and equilateral, the 
umbilici generally, though not always, slightly depressed, and the peripheral edge rounded. 
The septal bridges marking the retral processes are always more or less apparent, and in 
good examples they are conspicuous and regularly arranged (fig. 22). The aperture is 
ordinarily an arched crevice, sometimes notched along the superior margin, or, more 
rarely, divided by transverse bars so as to form a line of small pores. 
Polystomella striatopunctata is by far the most abundant and most widely dispersed 
variety of the genus. It is equally at home in the Arctic Ocean, the North and South 
Atlantic, the Mediterranean, the Adriatic, the Red Sea, the Indian and Southern Oceans, 
and the North and South Pacific. It stretches northwards to latitude 82° 33' N. in 
Smith Sound, and to about lat. 80° N. on the shores of Franz-Joseph Land; and south- 
wards to the Falkland Islands and Kerguelen Island. Its normal habitat is on bottoms 
of less than 100 fathoms, but it is not unfrequent down to about 600 fathoms, and rare 
specimens have been met with at six Stations, of which the depths were more than 1000 
fathoms, and at two of more than 2000 fathoms. 
As a fossil the species has been obtained from the Eocene of the Paris Basin (Terquem), 
and the Nummulitic beds of Styria (Reuss) ; the Upper and Lower Oligocene of Germany 
and France (Reuss) ; the Miocene of Austria and Bavaria (d’Orbigny, Egger) ; the later 
Tertiaries of Italy (Seguenza, Terrigi), the Crag of Antwerp (Reuss), and of the east of 
England (Jones, Parker, and Brady) ; and from almost every deposit of Post-tertiary age 
of which the microzoa have been determined. 
Polystomella subnodosa , Munster, sp. (PL CX. fig. 1 , a.b.). 
Robulina subnodosa, Munster, 1838 ( fide Eoemer), Neues Jabrb. fur Min., &c., p. 391, 
pi. iii. fig. 61. 
Nonionina splendida, Boll, 1846, Geog. d. deutscb. Ostseelander, p. 177, pi. ii. fig. 15. 
Polystomella subnodosa, Eeuss, 1855, Sitzungsb. d. k. Ak. AViss. AVien, vol. xviii. p. 240, pi. iv. 
fig. 51, a.b. 
„ punctata, Terquem, 1878, M4m. Soc. g4ol. France, s4r. 3, vol. i. p. 16, pi. vi. 
fig. 7, a.b. 
The test of Polystomella subnodosa is biconvex, the periphery being sharp or 
