What is "orthoceras"

Orthoceras \Or*thoc"e*ras\, n. [NL., fr. Gr. 'orqo`s straight + ke`ras a horn.] (Paleon.) An extinct genus of Paleozoic Cephalopoda, having a long, straight, conical shell. The interior is divided into numerous chambers by transverse septa.

Orthoceras ("straight horn") is a genus of extinct nautiloid cephalopod. This genus is sometimes called Orthoceratites. Note it is sometimes misspelled as Orthocera, Orthocerus or Orthoceros .

Orthoceras fossils are common and have a global distribution, occurring in any marine rock, especially in limestone.

These are slender, elongate shells with the middle of the body chamber transversely constricted, and a subcentral orthochoanitic siphuncle. The surface is ornamented by a network of fine lirae . Many other very similar species are included under the genus Michelinoceras.

'Orthoceras ' is a genus of orchids native to Australia, New Zealand and New Caledonia. Two species are known:

• Orthoceras novae-zeelandiae (A.Rich.) M.A.Clem., D.L.Jones & Molloy - New Zealand
• Orthoceras strictum R.Br. - New South Wales, Queensland, South Australia, Tasmania, Victoria, New Zealand North Island, New Caledonia

Orthoceras may refer to :

• Orthoceras (cephalopod), an extinct cephalopod genus
• Orthoceras (plant), an orchid genus