344 
THE VOYAGE OF H.M.S. CHALLENGER. 
two forms- are alike-, but Trochammina ringens has no vestige of the punctation or reticula- 
tion of the inner surface of the shell that has been alluded to. in the description of 
Trochammina trullissata. 
Trochammina ringens is much rarer than the allied species,, and its area of distribu- 
tion does not appear to extend beyond the Atlantic. It was, I believe, first found by the 
Rev. A. M. Norman, 1 in one of the “Valorous.” dredgings, at the entrance of Davis Strait, 
depth 1750 fathoms. Its occurrence has been noted at four points in mid-ocean in the 
North Atlantic, 1675 to 2750 fathoms, and at two points in the South Atlantic, 1900 and 
2350 fathoms ; from which it will be seen that it has not hitherto been met with on 
bottoms of less depth than 1600 fathoms. 
Trpchammina galeata., II. B, Brady (PL XL. figs. 19-23), 
Trochammina gcdeaia , Brady, 1881, Quart. Journ, Mier. Sci., voL xxi., N. S», p. 52. 
Test nautiloid and- symmetrical, subglob ular or compressed, showing only three 
segments externally, of which the last-formed constitutes much more than half the visible 
-shell. Aperture 1 situated on the peripheral face of the final segment, near its junction 
with the antepenultimate- ; simple, often immediately below a projection of the shell- wall. 
Diameter, A^-th inch (0-5 mm.). 
In many particulars this, species resembles Trochanvmina ringens, but it is scarcely 
so large-, and is relatively thicker ; its few segments, and the disproportionate size and 
embracing contour of the latest, are sufficiently distinctive. 
Trochammina galeata is a rare and somewhat inconspicuous form, only found at 
great depths in mid-ocean. Its distribution list includes eight Challenger Stations, of 
which three are in the North Atlantic, two in the South Atlantic, two in the South 
Pacific, and one in the North Pacific, the entire range of depth being from 182.5 fathoms 
to 2750 fathoms, 
Trochammina pcmctioculata, H. B. Brady (Pi. XL I, figs. 1, 2). 
Trochammina pauciloculata, Brady, 1879, Quart. Jeurii. Micr. Sci., vol. xix., N. S., p. 58, 
pi. v. figs. 13, 14. 
Test ovoid, slightly compressed, obscurely spiral composed of aho.ut two convolutions, 
the later of which almost entirely conceals the earlier one. Segments, few, usually three 
in each convolution, inflated ; sutures slightly constricted. Test thin, finely arenaceous, 
brown ; exterior surface smooth, often polished ;• interior smooth. Aperture a curved slit 
1 Mentioned by Mr. Norman, in the “Valorous” Report ( Proc . Roy. Soc., 1876, vol. xxv. p. 213), as “very near 
to, if not identical with., Globigerina arenaria,” a view which was abandoned after the examination of specimens of 
that species- furnished by Dr. Karrer. 
