340 
THE VOYAGE OF H.M.S. CHALLENGER. 
Hungarian North-Polar Expedition, off Franz-Josef Land, 113 fathoms, and amongst 
Capt. Markham’s soundings in shallow water on the shores of Novaya Zemlya. The Eev. 
A. M. Norman has collected the species at two points near Bergen on the coast of 
Norway, — south of Bukken, 150 to 210 fathoms, and Oster Fiord, 50 to 200 fathoms. 
Finally, it has been noticed at three Challenger Stations ; namely, — off Cape de Yerde 
Islands, 1070 fathoms; off Nightingale Island, Tristan d’Acnnha, 100 to 150 fathoms; 
and off Prince Edward Island, 50 to 100 fathoms 
Trochammina coronata, H. B. Brady (PI. XL. figs. 10-12). 
Trochammina coronata,. Brady, 1879, Quart. Journ. Micr. Sci., vol. xix., N. S., p. 58, pi. v. 
fig. 15. 
Test spiral, nautiloid, biconcave ; composed of three to six convolutions, all more 
or less visible externally ; . peripheral edge rounded and lobulate ; segments numerous, 
about six or seven in the final whorl, distinct, inflated. Aperture simple, situate on the 
face of the terminal segment, near its junction with the previous convolution. Colour 
buff to reddish-brown, . surface smooth, not polished. Diameter, ^th inch (2 - 5 mm.). 
This handsome species differs from its congeners in size as well as in general contour. 
The larger specimens are fully one-tenth of an inch in diameter, and are coronate 
or biconcave in form. The chambers are few in number, tent-like, and more or less 
embracing, though the successive convolutions do not entirely conceal those immediately 
preceding them. The width of the spiral band increases with each turn, and the 
chambers of the final whorl are large and prominent as compared with those of the earlier 
convolutions. The texture of the test is uniformly very finely arenaceous and opaque, but 
the colour varies a good deal within certain limits, namely from creamy white to dark brown. 
Amongst previously described Foraminifera it is not easy to find any with characters 
approaching those of Trochammina coronata ; perhaps the nearest is Trochammina injlata, 
but in that species the test is Botaliform, that is to say, all the segments are more or less 
exposed on the superior face, whilst those of the last convolution only are visible on the 
inferior side, — a feature sufficiently distinct from the symmetrical nautiloid habit of the 
present form. 
In geographical distribution Trochammina coronata is associated with its congeners 
Trochammina conglohata, Trochammina lituiformis, and Trochammina. \ proteus. It has 
been found at two Stations in the North Atlantic, — off Sombrero Island, West Indies, 450 
fathoms; and off Culebra Island, 390 fathoms; and at one in the South Atlantic, — off 
Pernambuco 675 fathoms. Rare specimens, presenting similar morphological characters, 
but of comparatively minute dimensions, have been met with in one of the deepest North 
Pacific soundings — Station 238, depth 3950 fathoms. 
