114 
NAUTILOIDEA. 
EemarTcs. This species resembles the 0. cinctum of Sowerby, and 
the 0. Morrisianum of de Koninck, but it is easily distinguished by 
its lesser transverse diameter, by the submarginal position of its 
siphuncle, and by its much slower rate of tapering. 
Horizon. Calcaire Carbonifere (Assise vi.) = Carboniferous Lime- 
stone. 
Locality. Vise, Belgium. 
Tolerably well represented in the Collection. 
Orthoceras Morrisianum, de Koninck. 
1851. Orthoceras Morrisianum^ de Koninck, Descrip, des Anim. Fossiles 
de la Belgique (Supplement), p. 55, pi. lix. f. 4. 
1880. Orthoceras Morrisianum, de Koninck, Faune du Calc. Carboni- 
fere de la Belgique, p. 69, pi. xl. f. 3. 
Sp, Char. Shell straight. Section elliptical, perhaps by compres- 
sion. Kate of increase about 1 in 9. Septa deep, and separated 
from one another by intervals which are nearly equal to 5 of the 
transverse diameter. The body-chamber is very spacious, and 
occupies nearly ^ of the total length. The siphuncle is narrow and 
central. The whole of the surface of the test is covered transversely 
with fine, thread-like lines, very regularly disposed. 
Uemarhs. This species resembles in its ornamentation the 0. con- 
questum and 0. salutatain of de Koninck, but it differs from these 
in the central position of its siphuncle as well as by its much greater 
size. With the 0. cinctum of Sowerby it may also be compared, 
but, judging by the figure in the ^Mineral Concholog}^’ Sowerby’s 
species has much coarser ornamentation than 0. Morrisianum. 
Horizon. Calcaire Carbonifere (Assise vi.) = Carboniferous Lime- 
stone. 
Locality. Vise, Belgium. 
Represented in the Collection by one fairly good specimen. 
Orthoceras Gesneri, Martin, sp. 
1809. Conchyliolithus Nautilites Oi-ihoceratites {Gesneri), Martin, Petri- 
ficata Derbiensia, p. 17, pi. xxxviii. fi*. 1, 2 (f. 2, young?). 
1828. Orthocera Gesneri, Fleming, British Anim. p. 239. 
1836. Orthoceras Gesneri, Quenstedt, De Kotis Nautil. primar. p. 20. 
1836. Orthoceras Gesneri, Phillips, Geol. of Y^orkshire, pt. ii. p. 239, 
pi. xxi. f. 6. 
1843. Orthoceras Gesneri ?, Portlock, Report on the Geol. of London- 
derry, p. 390. 
1844. Cyrtoceras tuberculatum, M‘Coy, Carboniferous Foss, of Ireland, 
p. 11, pi. iv. f. 2. 
