190 
NATJTILOIDEA. 
types figured by Sowerby in the ‘Mineral Conchology,’ and also 
Phillip’s type figured in the ‘ Geology of Yorkshire.’ A fine longi- 
tudinal section, showing the siphuncle, in a slab of polished marble 
was presented to the Museum by Prancis Wright, Esq.; another very 
fine example formed originally part of Dr. Mantell’s collection. 
Actinoceras striatum, Sowerby, sp. 
1814. Orthocera striata^ Sowerby, IMineral Conch, vol. i. p. 129, 
tab. Iviii. 
1836. Orthocerasundulatum, Phillips, Geol. of Yorkshire, pt. ii. p. 238, 
pi. xxi. f. 8. {Not of Sowerby.) 
1844. Orthoceras lineare, de Koninck, Descrip, des Anim. Fossiles de la 
Belgique, p. 619, pi. xliv. f. 6. {Not of Munster.) 
1844. Orthoceras lineale, de Koninck, ibid., Exphcation de la plancbe 
xliv. 
1849. Orthoceratites suhUneans, d’Orbigny, Prodr. de Paleont. Strati- 
graphique, vol. i. p. 1 13. 
1852. Orthoceras lineale^ Giebel, Fauna der Vorwelt, Band iii. Abth. i. 
p. 260. 
? 1852. Orthoceras striatum, M‘Coy, British Pal. Foss. fasc. ii. p. 405. 
1855. Orthoceras {Loxoceras) latcrale, M‘Coy, British Pal. Foss, 
fasc. iii. p. 572. {Not of Phillips.) 
1880. Orthoceras lineale, de Koninck, Faune du Calc. Carbonifere de la 
Belgique, tom. v. p. 79, pi. xli. fi*. 9, 9 a-c, pi. xliii. fi*. 8, 8 a-c. 
Sp. Char. Shell straight. Section oval, the ratio of the two 
diameters being as 26 : 33 in a somewhat compressed example, and 
as 19 : 22 in one which is apparently uncompressed. Bate of 
tapering from 1 in 6 to 1 in 5. Septa not very distant, their dis- 
tance about i of the transverse diameter, forming a broad and 
shallow sinus on that side of the shell which corresponds with the 
longer diameter, and is nearest to the siphuncle. The latter is 
nummuloidal, of medium size, and is situated about f across the 
shorter diameter, being equidistant from either extremity of the 
longer diameter. The external surface of the test is ornamented 
with a great number of longitudinal subparallel, nearly equidistant, 
straight striae, four or five' of which occupy the space of 1 line. 
Ko trace of any transverse striae or lines of growth is perceptible. 
Remarhs. M. de Koninck admits that he at first supposed that his 
species was identical with Sowerby’s. The differences by which he 
subsequently distinguished between the two can be easily reconciled. 
The first is an alleged difference in size in favour of 0. lineale, the 
second the nummuloidal form of the siphuncle in the latter. To 
the first of these characters very slight importance need be attached, 
