200 
THE VOYAGE OF H.M.S. CHALLENGER. 
long narrow slit, corresponding to a transverse section of the widened tube. The shell 
often attains comparatively large dimensions, and some specimens dredged in the Faroe 
Channel measure as much as ■§• inch (8 "5 mm.) in diameter. 
The typical Cornuspira foliacea, though found sparingly in almost every part of the 
world, is more particularly a North Atlantic species, and consequently is of much more 
common occurrence in the “ Porcupine ” dredgings than in the material brought home 
from the Challenger expedition. It has been met with at six Challenger Stations, of 
which three are in the North Atlantic; one in the South Atlantic, off Pernambuco, 350 
fathoms ; and two amongst the Australasian Islands, namely, off Paine Island, 155 fathoms, 
and off Kandavu, 210-255 fathoms. It is generally distributed over the area embraced 
by the three cruises of the “ Porcupine ” and is not uncommon on our own coast. Its 
bathymetrical range extends from shallow water to about 1500 fathoms, without much 
reference to bottom temperature, the finest specimens being found at from 300 to 
600 fathoms. 
The geological history of Cornuspira foliacea does not extend beyond the Tertiary 
epoch. It occurs in the Eocene “ calcaire grossier ” of the environs of Paris (Parker and 
Jones), in the Miocene of the Vienna Basin (Czjzek), in the Septaria-clays of North 
Germany (Reuss), in the later Tertiaries of Southern Italy (Costa, Seguenza), in the Crag 
of Suffolk (Searles Wood), and in the Post -tertiary deposits of Norway (Crosskey 
and Robertson), of the west of Scotland (Robertson), and of the north-east of 
Ireland (Wright). 
Cornuspira involvens, Reuss (PI. XI. figs. 1-3). 
Operculina involvens, Reuss, 1849, Denkschr. d. k. Akad. Wiss. Wien, vol. i. p. 370 pi. xlv. 
fig. 20. 
Cornuspira involvens , Reuss, 1863, Sitzungsb. d. k. Ak. Wiss. Wien, vol. xlviii. p. 39, pi. 
i. fig. 2. 
„ „ Jones, Parker, and Brady, 1866, Monogr. Foram. Crag, p. 3, pi. iii. 
figs. 52-54. 
Cornuspira involvens differs from the typical Cornuspira foliacea in its general contour. 
The two surfaces of the shell are concave and the peripheral edge is thick and rounded ; 
the convolutions become gradually stouter as they succeed each other and are somewhat 
embracing, instead of remaining thin and widening rapidly. The number of convolutions 
is very variable, but it is usually greater in the present species than in Cornuspira 
foliacea. The primordial end of the tube is sometimes swollen so as to form a sort of 
central chamber. It is often difficult to distinguish small specimens of Cornuspira involvens 
from minute annelids ; and shells having but few convolutions or presenting irregularities 
of structure, as well as all adherent specimens, are on that account to be regarded with 
