3G6 
THE VOYAGE OF H.M.S. CHALLENGER. 
in the tropics. The test is sometimes compressed throughout, and the distal end of 
long oval shape, as shown in PI. CXIII. fig. 1 ; but more commonly the later segments 
widen rapidly and the end is broadly elliptical. The walls are thin and non-labyrinthic, 
often somewhat arenaceous, and rough externally. The species differs from Textularia 
trochus in its simple, non-labyrinthic test, compressed contour, and roughish exterior. 
Textularia conica is a very generally diffused species, commonest perhaps on the coral- 
reefs of the Eastern Archipelago and the West Indies. 
Textularia trochus, d’Orbigny (PI. XLIII. figs. 15-19 ; PI. XLIY. figs. 1-3). - 
Textularia trochus, d’Orbigny, 1840, M6m. Soc. g6ol. France, vol. iv. p. 45, pi. iv. figs. 
25, 26. 
„ cuneiformis, var. conica, Williamson, 1858, Rec. For. Gt. Br., p. 75, pi. vi. 
figs. 160, 161. 
„ trochus, Jones, Parker, and Brady, 1865, Foram. Crag., pi. iii. figs. 17, 18. 
„ „ Vanden Broeck, 1876, Ann. Soc. Belg. Micr., vol. ii. p. 132, pi. iii. 
figs. 11, 12. 
Under the term Textularia trochus may be included all the shorter conical varieties 
of the genus that are circular in transverse section from the commencement. Generally 
speaking, the height of the test is but little greater than the diameter at the oral end, 
and is sometimes much less. Under favourable conditions, the walls exhibit a tendency 
to become thick and labyrinthic, and the sutures limbate externally. The length (or 
height) seldom exceeds -^gth inch (1 mm.). These characters are sufficient to distinguish 
the species from the closely-allied Textularia turris, Textularia conica, and Textularia 
barrettii. 
Textularia trochus is a cosmopolitan form, reaching its highest development in tropical 
and subtropical latitudes, and its greatest abundance amongst coral-sands. 
It is well known as a Cretaceous fossil ; and has been observed in the later Tertiary 
deposits of Sicily and in the Crag of the east of England. 
Textularia turris, d’Orbigny (PI. XLIY. figs. 4, 5). 
Textularia turris, d’Orbigny, 1840, M£m. Soc. g6ol. France, vol. iv. p. 46, pi. iv. figs. 27, 28. 
„ „ Parker and Jones, 1863, Ann. and Mag. Nat. Hist., ser. 3, vol. xi. p. 97. 
Textularia turris is round in transverse section, elongate, and tapering. It differs 
from Textularia trochus chiefly in its greater proportionate length and its rougher 
exterior, as well as in its frequent irregularity of contour. Eecent specimens are some- 
times -^-th or even ^-th inch (3 to 4 mm.) in length. 
Well-marked examples of Textularia turris are rare in the living condition. It has 
