6 
NAFTILOIDEA. 
? 1840. Orthoeeratites regularise Miinster, Beitrage ziir Petrefacteii- 
kunde, Heft iii. p. 95, Taf. xyii. ff. 3, 4. 
1853. Orthoceras regulars, Geinitz, Die Verstein. der Grauwackeuform. 
in Sachsen, Heft ii. p. 27, Taf. i. f. 12. 
1857. Orthoceras regulars, ^o\\, Beitrag zur Kenntniss der Siliir. Ceph. 
in Archiv fiir die Naturkunde von Mecklenburg, p. 14, Taf. iii. 
ff. 7, a, h, c. 
1860. Orthoceras regulars, Eichwald, Lethsea Kossica, Seconde Sec- 
tion, vol. i. p. 1198. 
1861. ?, Ferd. Eoemer, Die fossile Fauna der sil. 
Diluvial-Geschiebe von Sadewitz, p. 57, Taf. vii. ff. 5, a, h. 
1869. Orthoceras regular e, Karsten, Die Verstein. des Uebergangsge- 
birges in den Gerollen der Herzogthiimer Schleswig und Holstein, 
p. 46, tab. XV. if. 8, a-e. 
? 1869. Orthoceras regulare, Heidenhain, Ueber Graptolithen fiihrende 
Diluvial-Geschiebe der norddeutschen Ebene, p. 21. 
? 1878. Orthoceras commutatum (pars), Kayser, Abhandl. zur geol. 
Specialkarte von Preussen, p, 69, Taf. xi. ff 4, 4 a. 
? 1878. Orthoceras regulare, Haupt, Die Fauna des Graptolithens 
Gesteines, p. 51. 
? 1880. Orthoceras regulare, Angelin-Lindstrom, Fragin. Silurica, p. 4, 
tab. iv. ff. 4, 5. 
1880. Orthoceras regulare, Dewitz, Beitrage zur Kenntniss der in den 
Ostpreussischen Silurgeschieben vorkominenden Ceph. in Schrift. d. 
phys.-okon. Gesellsch. zu Konigsberg, Abth. ii. p. 165, ff. 2, 3. 
1880. Orthoceras regulare, Kjerulf, Die Geol. des siidlichen und mitt- 
leren Norwegen (deutsche Ausgabe von A. Gurlt), p. 68. 
[Ah^ Orthoeeratites regularis, Hisinger, 1837, Leth. Suec. p. 29, tab. ix. 
f. 3. Orthoeeratites regularis, Qiienstedt, 1846, Petref. Deutschl. 
Bd. i. Abth. i. p. 43, tab. i. f. 1. Orthoceras regulare, G. & F. Sandb. 
Die Verstein. des rhein. Schicht. in Nassau, p. 173, Taf. xx. ff. 2, 
2 a, bis 2 /.] 
Np. Char. The species has a central siphuncle and somewhat 
remote, strongly convex septa. In a specimen having a maximum 
diameter of 1 inch, they are about \ an inch apart. The rate of 
tapering is slow, about 1 in 17. The surface of the test is trans- 
versely striated. 
Bemarhs. Schlotheim’s description is very brief and insufficient ; 
it runs thus : — “ 0. regulare is distinguished chiefly by its perfectly 
round, very slender, nearly central siphuncle. The septa are slightly 
curved and not very close together. It appears to attain a con- 
siderable length and thickness.” 8chlotheim’s reference to Breyn’s 
excellent figures has enabled authors to recognize the species, though 
it is evident from the synonymy that several forms have been erro- 
neously included under this name. Most of the examples known 
are imperfect. 
