658 
THE VOYAGE OF H.M.S. CHALLENGER. 
Plcmorbulina larvata, Parker and Jones (Pl. XCII. figs. 5, 6). 
Planorbulina vulgaris, var. larvata, Parker and Jones, 1860, Ann. and Mag. Nat. Hist., ser. 3, 
vol. v. p. 294. 
„ larvata, Id., 1865, Phil. Trans., vol. clv. p. 379, pl. xix. fig. 3, a. h. 
This is a symmetrically-formed parasitic variety, characterised by its relatively thick 
walls and the granular or tuberculate condition of the exterior, especially near the centre 
of the disk. The segmentation is often indistinct externally, but the marginal apertures 
are generally well defined and conspicuous. 
Planorbulina larvata is an exclusively tropical species. It occurs at seven Stations 
amongst the islands of the South Pacific, at depths varying from 15 to 210 fathoms, 
chiefly in coral-sands. It has also been obtained from the Honolulu Reefs, 40 fathoms, 
and from the Chinese Sea. 
Truncatulina, d’ Orbigny . 
Nautilus, pars,. Walker and Boys [1784], Fichtel and Moll, Maton and Rackelt,.Turton, Pennant, 
Hillwyn. 
Serpula, pars, Montagu [1803], 
Rotalia, pars, Lamarck [1804], d’Qrbigny, .Roemer, Reuss, Karrer, Staclie,. Giimbel. 
Polyxenus, Montfort [1808]. 
Cibicides, Montfort [1808], Blainville. 
Cristellaria, pars, Lamarck [1822]. 
Truncatulina, d’Orbigny [1826], Bronn, Munster, Roemer, Reuss, Costa, Egger, Parker and 
Jones, Williamson, Karrer, Seguenza, Brady, Dawson, M. Sars, Hantken, Wintker, Wright, 
> Terquem, &c. 
Lobatula, Fleming [1828], Thorpe. 
Rosalina, pars, d’Orbigny [1839], Alth, Reuss, Stache, Giimbel. 
Rotalina,, pars, d’Orbigny [1839], Czjzek, Reuss, Bailey, Bornemann, Egger, Karrer, Seguenza, 
Martonfi. 
Piscorbis,. Macgillivray [1843]. 
Anomalina, pars, d’Orbigny [1846], Schwager, 
Siphonina, Reuss [1849], Costa, Karrer, Terrigi, Seguenzai 
Planorbulina, pars, Parker and Jones [1860], Carpenter, Brady, Siddall. 
In the arrangement which has been followed, the Truncatuline group of Planorbulince 
is limited to those species in which the spire is either Rotaliform, that is to say, 
completely involute on the inferior aspect and e volute on the superior, or else more or 
less involute on both sides.. Such varieties find their typical representative in the 
common Truncatulina lobatula , — a plano-convex shell of parasitic habit, growing adherent 
by its flat superior face. By imperceptible gradations the plano-convex forms pass into 
the biconvex, some of which, like Truncatulina hauling erii, retain the Rotaliform 
disposition of the segments, whilst others, such as Truncatulina rostrcita, become almost 
Nummuline in the embracing contour and bilateral symmetry of the convolutions. 
