NAUTILOTDEA. 
2b 
Orthoceras Ludense, Sowerby. 
1839. Orthoceras Ludense, Sowerby, in Murchison's Sil. Syst. p. 619, 
pi. ix. ff. la,\h. 
1852. Orthoceras Ludense, M'Coy, British Pal. Foss. fasc. ii. p. 315. 
1854. Orthoceras Ludense, Salter, in Murchison's ‘ Siluria,’ Foss. 
Gr. 44. f. 2. 
1857. Orthoceras columnar e, Boll, Archiv fur die Naturkunde von 
Mecklenburg', p. 16, Taf. i. fF. ?>a, 36. 
1866. Orthoceras temper ans, Barrande, Syst. Sil. de la Boheme, Tol. ii. 
Texte iii. 1874 (janvier), p. 658, pi. ccxxx. ff. 7-9, pi. cccxxvii. 
ff. 1, 2, pi. ccclxxxii., pi. ccccli. ff. 1-3. 
1870. Orthoceras Dahlli, Barrande, loc. cit. pi. ccccxl. ff. 7-10. 
1870. Orthoceras columnare, Barrande, loc. cit. p. 697, pi. ccccxlii. ff. 1, 2. 
1873. Orthoceras Ludense, Salter, Cat. Cambr. and Sil. Foss. p. 158. 
1880. Orthoceras columnare, Angelin and Lindstrom, Fragmenta 
Silurica, p. 7, tab. v. ff. 1, 2, 5, 6. 
1882. Orthoceras Ludense, Blake, British Foss. Ceph. pt. i. p. 156, 
pi. X. ff. 1, 3, 4, 5, 7. 
[Not 1841. Orthoceras Ludense, Phillips, Pal. Foss, of Cornwall, Devon, 
and West Somerset, p. 110, pi. xlii. f. 206, a, h, c. — 1867. Ortho- 
ceras columnare, Hall, 20th Reg. Rep. p. 351, pi. xix. (x.) ff. 4, 5, 
6 , 8 .] 
Bp. Char. Section circular. Rate of increase 1 in 12. Septa 
direct, or slightly undulating in some specimens (for these last 
Professor Blake proposes the varietal name undidata), distant the 
diameter. Body-chamber of considerable length ; one measured by 
Professor Blake reaching inches in length. Siphuncle a little 
eccentric, and placed along the diameter. Surface marked only 
by obscure lines of growth. 
Remarhs. This species attains a great length ; the longest in the 
National Collection measures 15| inches ; and Blake estimates that 
some individuals may have reached 4| feet. It is a widely distri- 
buted species^ as a glance at the synonymy will show. 
Horizon. Lower (?) and Upper Ludlow. 
Localities. British ; Ludlow, Shropshire ; Herefordshire. — 
Foreign ; Island of Gothland, Sweden. 
Represented by very fine specimens, two of them figured by Blake 
{loc. cit.). 
OHhbceras distans, Sowerby. 
1839. Orthoceras distans, Sowerby, in Murchison’s Sil. Syst. p. 619, 
pi. viii. f. 17. 
1866. Orthoceras migrans, Barrande, Syst. Sil. de la Boheme, vol. ii. 
Texte iii. 1874 (janvier), p. 643, pi. ccxii. ff. 1-4, pk eexxii. ff. 1,2, 
pi. cceix. ff. 1-4, pi. cccxlviii., pi. ccclxxvii. 
