112 
XAIJTILOIDEA. 
Orthoceras ? cucullus, de Koninck. 
185]. Orthoceras cucullus, de Koninck, Descr. des Anim. Fossiles de la 
Belgique (Supplement), p. 54, pi. lix. f. I, a, h. 
1880. Orthoceras cucullus^ de Koninck, Faune du Calc. Carbonifere de 
la Belgique, p. 64, pi. xlv. f. 1. 
Bp. Char. Shell straight, but not regularly conical. The trans- 
verse section represents an ellipse the ratio of whose axes is about as 
10 : 7, but this may be due to compression. The rate of tapering 
is very rapid, being about 1 in 2-|. The septa are somewhat 
shallow and moderately distant ; they form a broad and shallow 
sinus on one side and curve rapidly upwards laterally. The 
siphuncle, of which the diameter is about \\ line, is situated f 
across the smaller axis of the ellipse. 
The surface of the test is perfectly smooth. 
Bemarlcs. This may be an Actinoceras. In the undulating form 
of the septa it resembles Actinoc. striatum.^ Sow., but its remarkably 
rapid rate of increase distinguishes it completely from that and other 
allied species. 
The specimen in the National Collection being partly buried 
in the matrix, the siphuncle cannot be made out, and this informa- 
tion is necessary before any definite conclusion can be come to as to 
its affinities. At present I place it in the genus Orthoceras. 
M. de Koninck makes no allusion in his description to the undu- 
lation of the septa, and figures them as if they were direct. He 
says that he was acquainted with but one specimen of the species, 
which he himself collected in the “ Calcaire Carbonifere” of Vise 
(Assise vi.). 
Horizon. Calcaire Carbonifere de Vise = Carboniferous Limestone. 
Locality. Yise, Belgium. 
Fairly well represented in the Collection. 
Orthoceras Goldfussianum, de Koninck. 
1843. Orthoceras Goldfussianus, de Koninck, Precis elem. de G^ologie, 
par J. J. d’Omalius, p. 516. 
1844. Orthoceras Goldfussianum, de Koninck, Descrip, des Anim. Fos- 
siles de la Belgique, p. 510, pi. xliii. ff". 3, 4. 
1844. Orthoceras {Loxoceras) incomitatum, M‘Coy, Carboniferous Lime- 
stone Foss, of Ireland, p. 9, pi. i. f. 6. 
1849. Orthoceratites Goldfussianus, d’Orbigny, Prodr. de Paleont. 
Stratigraphique, vol. i. p. 112. 
1851. Orthoceras Goldfussianum, Giebel, Fauna der Vorwelt, Band iii. 
Abth. i. p. 245. 
