ORDER II. MONOTHALAMIA. 305 
and simply involuted. They are few in number, and included in the fol- 
lowing genus : 
ARGONAUTA. 
ARGONAUTA, Linneus. 
Testa subnavicularis, illoculosa, papyracea, tenuissima, in spiram discoi- 
deam leviter convoluta ; spira bicarinata, propé in teste aperturam 
subimmersa ; carinis plus minusve tuberculosis. 
The Nautilus primus, or ‘‘ Paper Nautilus” of Aristotle, was separated 
about the middle of the eighteenth century from his Nautilus secundus, or 
‘Pearly Nautilus,” by Gualtieri, an Italian conchologist, under the title 
of Cymbium: it was distinguished too by his Swedish contemporary Lin- 
neus about the same time under that of Argonauta ; and the increasing 
celebrity of that writer soon obtained for his name the preference. The 
observations of those authors were, however, still confined to the shell ; 
the Professor of Pisa added little more to the early history of the Argo- 
naut than the Professor of Upsal; and the zoological world was warmly 
divided on the nature and affinities of its inhabitant. Bruguiére, La- 
marck, De Montford, Ocken, De Roissy, Leach, Cuvier, De Férussac, 
De Blainville, Rafinesque, Deshayes, and Gray advanced little beyond a 
speculative series of hypothetical arguments, the final observations of 
Lamarck being the most accurate because least hypothetical. The com- 
plete demonstration of this animal was singularly reserved for the skilful 
anatomist of the ‘‘ Pearly Nautilus,” for its true relation and character 
was established only five years since by the very laudable exertions of 
Mr. Owen. 
The body of the Argonaut retains so little muscular adhesion with the 
shell, and presents altogether such an apparent anomaly of structure, that 
the learned were for a long time suspicious of their natural relation ; they 
believed that the octopodous Cephalopod usually found with this elastic 
envelope was neither its fabricator nor lawful owner. Some indulged a 
