72 
NAUTILOIBEA. 
With this view T do not hesitate to concur, and in further support 
of it I may mention the following facts. I have ascertained by 
means of natural and artificial sections that the siphuncle in this 
species deviates gradually from a position close to the margin in the 
young shell to one nearer the centre as growth advances. These 
two positions of the siphuncle are shown in fig. 7, h and /. This 
may account for Wahlenberg’s statement that his species has a 
central siphuncle. In the very figures, moreover, to which he refers 
in his description, viz. those of Klein (7oc. cit.), the siphuncle is repre- 
sented, not as central, but exactly in the position it occupies in fig. 7, h. 
Horizon. Etage E, bande e 2 (= Salopian). Epper Ludlow 
(Sweden). 
Localities. Wiskocilka, Bohemia ; Island of Gothland, Sweden. 
Well represented in the Collection. 
Orthoceras iilosum, Sowerby. 
1839. Orthoceras flosum, Sowerby, in Murchison’s Silurian System, 
p. 620, pi. ix. f. 3. 
1852. Orthoceras Jiloszim, M‘Coy, British Pal. Foss. fasc. ii. p. 314. 
1854. Orthoceras filosum, Salter, in Murchison’s Siluvia, p. 231, 
Foss. 44. f. 1. 
1873. Orthoceras Jilosum, Salter, Cat. Camhr. and Sil. Foss. p. 173. 
1882. Orthoceras Jilosum, Blake, British Foss. Cepli. pt. i. p. 113, pi. x. 
tr. 8, 9. 
\_Not 1880. Orthoceras jilosum, L.-G. de Koninck, Faune du Calcaire 
Carhonifere de la Belgique, in Ann. du Musee Royal d’llist. Xat. 
de Belgique, tome v. p. 58, pi. xxxviii. f. 7, pi. xliv. f. 1.] 
Char. Shell slightly curved. Section circular, though 
generally compressed. Rate of increase from 1 in 5 to 1 in 12 in 
the body-chamber. The latter attains to a length equal to 4 times 
the diameter of its base. The septa are direct, and distant about |- 
the diameter at the smaller end, but become closer near the body- 
chamber. The siphuncle is central. The ornaments consist of 
longitudinal riblets upon the flat surface of the shell, so close 
together as to number 142 in the circumference of a small specimen 
and 115 in that of a large one. Their distance in the former is | a 
line, in the latter 1 line. There are no intermediate ornaments. 
Remarlcs. This species attains a large size. One in the British 
Museum is 1 foot in length, but Professor Blake records an example 
in the Ludlow Museum over 2 feet in length. 
Horizon. Wenlock Limestone; Lower Ludlow. 
Localities. Dudley, Worcestershire ; Mocktree Forest, Leintwar- 
dine, Herefordshire. 
Well represented in the Collection. 
