552 
THE VOYAGE OF H.M.S. CHALLENGER. 
Fichtel and Moll employ the Linnsean name for a somewhat less extensive 
morphological series, and illustrate the species by drawings of twelve varieties, including 
only those forms which have acute, carinate, or rowelled margins, the round-edged 
modifications being otherwise provided for. 
It is evident that the specific term “ calcar ” was intended to refer to the spinous 
periphery ; and in distinguishing by name the different varieties originally allotted to 
the specific group, the most natural course is to restrict its application to the most 
typical of the carinate and rowelled forms. This view has been adopted by d’Orbigny 
and many subsequent writers. 
With this limitation, the shell of the typical Cristellaria calcar may be characterised 
as biconvex or lenticular in form, more or less carinate, and armed with a number of 
radiating peripheral teeth or spines. The sutures are sometimes slightly limbate, but 
otherwise the exterior is smooth and destitute of ornament. The width of the keel 
and the length of the spines vary in different specimens, as may be seen by the figures. 
Good specimens of Cristellaria calcar have been found at three Stations in the North 
Atlantic — off Sombrero Island, West Indies, 450 fathoms, off Culebra Island, West Indies, 
390 fathoms, and off the Azores, 450 fathoms ; at five localities amongst the islands of the 
South Pacific, depth from 129 fathoms to 580 fathoms ; and at one in the North Pacific, 
off the Philippines, 95 fathoms. The species occurs also in the Mediterranean and the 
Adriatic. 
In the fossil condition it appears in various formations of middle and later Tertiary 
age in Germany, Austria, Italy, Spain, and elsewhere. 
Cristellaria cassis, Fichtel and Moll, sp. (PI. LXVIII. fig. 10). 
“Cornu Hammonis,” Plancus, 1760, Conch. Min., ed. altera, p. 120, pi. i. fig. xi. 
“ Litui crispati et orbiculi,” Soldani, 1789, Testaceographia, vol. i., pt. 1, p. 63, pi. lvi. figs. I.K., &c. 
Nautilus cassis, Fichtel and Moll, 1803, Test. Micr., p. 95, pi. xvii, 
Linthuris cassidatus, Montfort, 1808, Conch. Syst., vol. i. p. 254, 64 e genre. 
Cristellaria cassis, Lamarck, 1816, Tahl. Encycl. et Method., pi. cccclxvii. fig. 3, a-d. 
55 
producta, Id. 
Ibid. 
pi. cccclxvii. fig. 3, e-g. 
55 
serrata, Id. 
Ibid. 
pi. cccclxvii. fig. 4, a, b. 
55 
papilionacea, Id. 
Ibid. 
pi. cccclxvii. fig. 4, c, d. 
55 
undata, Id. 
Ibid. 
pi. cccclxvii. fig. 5, a-c. 
51 
papillosa, Id. 
1822, Anim. s. Vert., vol. 
vii. p. 607, No. 2. 
55 
Levis, Id. 
Ibid. 
p. 608, No. 3. 
Linthuris cassis, Blainville, 1825, Man. de Malacol., p. 384, pi. x. fig. 3. 
Cristellaria cassis, d’Orbigny, 1826, Ann. Sci. Nat., vol. vii. p. 290, No. 3. — Modele, No. 44. 
,, „ Parker, Jones, and Brady, 1871, Ann. and Mag. Nat. Hist., ser. 4, vol. viii. 
p. 244, pi. x. figs. 86, 87. 
Nautilus cassis, as depicted by Fichtel and Moll, is a thin compressed Cristellarian, 
with somewhat narrow chambers and a wide peripheral keel. Of the four individuals 
