258 
THE VOYAGE OF H.M.S. CHALLENGER. 
if at all contracted, constituting the general aperture. Walls comparatively thin, of 
uniform thickness throughout, compact, and firmly cemented ; often rough externally, but 
sometimes smooth or even polished ; interior smooth. Length, -^rd inch (8 mm.) or less. 
This species was first described in a short paper on the Foraminifera collected during 
the North-Polar Expedition of 1875-6, loc. cit. The arctic specimens were at that time 
supposed to be specifically identical with some of much larger size occurring in the 
“ Porcupine ” and Challenger dredgings ; these however have since been adopted as 
representatives of a distinct species (Hyperarnmina friabilis), and it has therefore been 
necessary to amend and somewhat to restrict the zoological characters originally given. 
Hyperarnmina elongata is one of the simplest of the arenaceous Foraminifera. The 
test, as already stated, consists of a cylindrical tube open at one end and closed at the other, 
the closed end being round and somewhat swollen. The diameter is nearly uniform, and 
seldom measures more than ^jth of an inch (0'42 mm.) and the length varies from -|th to 
■^rd of an inch (3 to 8 mm.), but the specimens are hardly ever found complete. The wall is 
of even thickness throughout, and there is no circumscribed or well defined primordial 
chamber. The texture is arenaceous, and the constituent sand-grains are firmly cemented 
together ; but the condition of the exterior varies considerably according to the nature of 
the material employed in the construction of the test — some specimens being rough like 
Rhabdammina, others smooth and polished like Trochammina, the generality having inter- 
mediate characters. Its small dimensions and slender build, and the comparatively thin 
and hard walls are sufficient to distinguish the species from Hyperarnmina friabilis. 
Hyperarnmina elongata is almost cosmopolitan. It is found as far north as latitude 
79° or 80°, both in Smith Sound and off Franz-Josef Land, at depths of from 80 to 130 
fathoms. It has been dredged on our own shores, off Cumbrae and in Portree Harbour 
(Robertson), and in Dublin Bay (Balkwill and Wright) ; as well as in both the warm aud 
cold areas of the Faroe Channel, 530 to 540 fathoms. It has been obtained at various 
Stations in the North Atlantic, at depths of from 410 to 1750 fathoms; in the South 
Atlantic, 350 to 2200 fathoms; in the North Pacific, 2300 and 3124 fathoms ; in the 
South Pacific, 410 to 1425 fathoms ; and lastly, from a single Station in the Southern 
Ocean, between the Cape of Good Hope and Kerguelen Island, 1570 fathoms. 
Hyperarnmina friabilis, n. sp. (PI. XXIII. figs. 1, 2, 3, 5, 6). 
Hyperarnmina elongata (pars) Brady, 1878, Ann. and Mag. Nat. Hist., ser. 5, vol. i. p. 433. 
„ „ Id. 1879, Quart. Journ. Micr. Sci., vol. xix. N. S., p. 32. 
Test free, elongate, subcylindrical, tapering, straight or nearly straight ; the wide 
end closed and rounded, the narrow end somewhat contracted so as to form a simple 
rounded aperture. Internal cavity commencing with a distinct subglobular chamber at 
