XAFTILID^. 
89 
1852. Xautilus Zeveilleamis, Gietel, Fauna der Yorwelt, Band iii. 
Abtli. i. p. 170. 
1854. Xautilus Leveilleanus, Morris, Cat. British Foss. 2nd ed. p. 309 
(excl. synon.). 
1854. Xautilus Leveilleanus, Pictet, Traite de Paleontologie, yoI. ii. 
p. 023, pi. 1. f. 3. 
1878. Xautilus Leveilleanus, de Koninck, Faune du Calcaire Carhouifere 
de la Belgique (Annales du Mus. Eoy. d’Hist. Xat. de Belgique, 
tom. ii.), pt. i. p. 143, pi. xxviii, ff. 0 a, 6 h, 6 c. 
Sj). Char. Shell discoid, '^ith a somewhat pointed apex, laterally 
compressed, composed of about four contiguous volutions, with a 
moderately large central vacuity. Transverse section subquadrau- 
gular, a little inflated at the sides, and somewhat depressed above and 
below. The section of the first and part of the second whorl is 
nearly circular. In consequence of the entire absence of angles or 
keels upon any part of the sides, the umbilicus is not well defined, 
nor is it deep. The septa are moderately concave ; their distance 
cannot be ascertained owing to all the known specimens being covered 
by the test. The siphuncle, as seen in the .specimen in tiie British 
Museum Collection, is situated close to the ventral border. The whole 
of the surface of the test is covered by fine, close-set, wavy lines of 
growth, which are quite visible to the naked eye. Tliese are crossed 
by somewhat stronger longitudinal lines, which cover the whole of the 
shell in the young, but only tlie upper part of the sides and the 
periphery in the adult. The intersection of the transverse and 
longitudinal lines gives a granular appearance to the sculpture, 
which is particularly noticeable in the young shell. 
liemarls. Some authors, says de Koninck, have confounded the 
present species with others, with which it is doubtless intimately 
connected, but from which it may, nevertheless, be readily distin- 
guished. Thus, Morris allies it with the iV. M‘Coy, 
which is a much larger shell, with tliicker whorls, rounded peri- 
phery, and much more coarsely ornamented. D’Orbigny also figures, 
under the name of X. Leveilleanus, a species in which the first 
whorls of the spire are much more slender and the striae of growtli 
stronger and less numerous than those of the present species. 
A fine example in the Collection gives the following measure- 
ments : — Greatest diameter of the shell 5 inches, of the umbilicus 
2| inches, of the outer volution a little over 1| inches. De Koninck 
gives admirable figures of this species (loc. cit.), which he says is 
rare in Belgium. 
Horizon. Calcaire Carbonifere Superieur (Assise vi.) = Carboni- 
ferous Limestone. 
