710 
THE VOYAGE OE H.M.S. CHALLENGER. 
The distinction between the genera Rotalia and Calcarina is founded by Carpenter 
upon the porous or divided aperture, and the “ extraordinary development of the supple- 
mental skeleton ” of the latter genus. If this view be accepted, and it appears to afford 
the only practicable basis of separation, the group of forms of which the present species 
may be taken as the type find their proper position in the genus Rotalia. The most 
familiar examples of the group referred to are Calcarina calcar, d’Orbigny, Calcarina 
pulchella, d’Orbigny, Rotalia armata, d’Orbigny, Rotalia bisaculecita, d’Orbigny, and 
Rotalia dentata, P. and J. ; whilst Calcarina defrancii, d’Orbigny, 1 furnishes an inter- 
mediate link connecting them, on the other hand with the true Calcarina. Excepting 
Calcarina 'pulchella, which has marginal spines originating in the earlier whorls, they 
are all characterised to a greater or less degree by the angular or pointed peripheral ends 
of the chambers ; and the test presents either a dentate or a zig-zag outline, according to 
the size and shape of the projecting angles. 
The drawing (PL CVIII. fig. 3) represents a well-marked typical specimen of Rotalia 
calcar ; the smaller shell (fig. 4) is a young example, either of the same species or of the 
closely-allied Rotalia dentata , Parker and Jones. 2 Between d’Orbigny’s models of 
Calcarina calcar and Rotalia armata I can detect no distinctive character of the least 
value. 
Rotalia calcar is not uncommon in the shallow water coral-sands of the East and 
West Indies ; it occurs also in the Mediterranean and the Red Sea ; on the shores of 
Madagascar, the Mauritius, and Ceylon, and at the Cape of Good Hope. 
Of its geological distribution I am unable to say more than that I have specimens 
from the Barton Beds (Eocene) of the Isle of Wight, and from the Miocene of Malta ; and 
that Terquem figures what is apparently the same species from the Eocene of the 
neighbourhood of Paris. 
Rotalia pulchella, d’Orbigny, sp. (PL CXY. fig. 8, a.b.). 
Calcarina pulchella, d’Orbigny, 1839, Eoram. Cuba, p. 92, pi. v. figs. 16-18. 
Rotalia pulchella, Parker and Jones, 1865, Phil. Trans., vol. civ. p. 387. 
This beautiful little species appears to belong to the Rotalian rather than the Cal- 
carine group. D’Orbigny’s figures represent a clear, thin-walled Rotaliform shell, the 
segmentation of which is quite distinct on both faces, and the aperture a somewhat large, 
undivided, arched fissure. But its most remarkable feature consists of three long slender 
spines, which have their origin in the septal bands of the earlier convolutions, and form 
nearly equidistant peripheral radii. The spines are solid, and smooth externally, 
1 Moebius figures, under the name Rotalia defrancei (Foram. von Mauritius, pi. xiv.), a variety which I should pre- 
fer to call Rotalia calccvr; hut his general conclusions as to the Rotalian affinity of the forms under consideration are the 
same as my own. 
2 Phil. Trans., vol. civ. p. 387, pi. xix. fig. 13, 1865. 
