NODOSARIA. 



Orthoceras and Nodosaria, Lam. 



TESTA polythalamia, recta, septis numerosis, 

 transversalibus, siphone central! vel lateral! 

 perforatis. 



The differences between Lamarck's Nodosaria and Ortho- 

 ceras are so slight that we do not hesitate to unite them 

 together under the generic name of JSTodosaria, and upon 

 reference to Sander Rang's Manuel des Mollusques we 

 find that other writers entertain the same opinion. It is 

 to be particularly observed that the minute cephalopodous 

 shells which Lamarck has called Orthocerata arfe quite 

 distinct from the remarkable fossils to which that name 

 is usually applied. We have also shown that these last 

 are closely united to the Belemnites, from which we do 

 not indeed think them properly separated, seeing that they 

 really differ in no circumstance except the thickness or 

 solidity of the lower part of the shell. 



For the present Genus we use the appropriate name 

 of Nodosaria in preference to Orthoceras, partly because 

 we wish thereby to prevent confusion, and partly because 

 we wish to leave Geologists in possession of the latter 

 term, which is so well applied to the remarkable fossils 

 which have usually borne it. 



We admit the Nodosariae without hesitation to a place 

 among the polythalamous MoUusca, although we are 

 entirely unacquainted with their animals, because we 



