no 
XAUTILOIDEA. 
Orthoceras subcanaliculatum, de Koninck. 
1844. Orthoceras subcanaliculatum, de Koninck, Descrip, des Anim. 
Fossiles de la Belgique, p. 519, pi. xWii. f. 5, a, b. 
1849. OrthoceraHtes subcanaliculatus, d’Orbigny, Prodr. de Paleont. 
Stratigraphique, vol. i. p. 113. 
Sp. Char. Shell straight or slightly curved. Section nearly 
circular. Septa very approximate, and very slightly convex. 
Siphuncle filiform, subcentral. Surface ornamented with about 
forty longitudinal smooth and prominent ridges, of which twenty 
are smaller and less elevated than the others, and alternate regularly 
with them. Between the larger and smaller ridges there are still 
finer ones, so that the whole of the shell-surface is covered with 
longitudinal lines. 
Horizon. L’Argile Carbonifere (Assise i.) = Carboniferous Lime- 
stone. 
Locality. Tournai, Belgium. 
Fairly well represented in the Collection. 
Orthoceras sagitta, de Koninck. 
1851. Orthoceras sayitta, de Koninck, Descrip, des Anim. Fos.^^iles 
de la Belgique (Supplement), p, 703, pi. lix. f. 3. 
1880. Orthoceras sagitta, de Koninck, Faune du Calc. Carbonifere de 
la Belgique, p. 51, pi. xxxviii. f. 4. 
Bp. Char. Shell straight, very long and slender. Section cir- 
cular. Bate of increase about 1 in 18. Septa pretty strongly 
convex, relatively very distant ; their distance equals nearly f of 
their transverse diameter. The body-chamber appears to have been 
very large, and to have occupied a little less than ^ of the total 
length of the shell. The siphuncle is filiform, and is situated close 
to the margin. The surface of the test shows no trace of striae or 
of other ornaments. 
Eemarhs. This species is distinguished from 0. calamus, 0. 
Martinianum, 0. tihiale, and 0. simile by the distance of its septa, 
as well as by the marginal position of its siphuncle. 
Horizon. Calcaire Carbonifere de Vise (Assise vi.) = Carboniferous 
Limestone. 
Locality. Vise, Belgium. 
Bepresented in the Collection by two fragments. 
Orthoceras Martinianum, de Koninck. 
1844. Orthoceras Martinianum, de Koninck, Descrip, des Anim. Fossiles 
de la Belgique, p. 505, pi. xliv. f. 4. 
