370 



pods ; to the former the Argonaut belongs. The Octopods are 

 all naked, without external shells, except the Argonaut. This 

 animal is the Nautilus of the ancients ; its shell, however, is not 

 chambered like that of the Nautilus. The Argonaut is found in 

 the Mediterranean and Indian Seas, and in the Atlantic and 

 Pacific Oceans, where the shell is often cast ashore by the 

 waves ; it is usually obtained without the animal, which, sinking 

 with its shell below the surface at the approach of danger, is 

 rarely captured by the general naturalist ; it is also said to be 

 nocturnal and crepuscular. The specimen exhibited was the 

 first ever seen here. 



The best known species of Argonaut are Argonauta argo, 

 Linn., A. nodosa, Solander, and A. Mans, Solander, One species 

 is found fossil in the pleiocene of Piedmont, very like A. argo, 

 but considered identical with A. Mans, now living in the ocean. 



Specimens of five species of shells were exhibited from the 

 Society's and Dr. Warren's collections. The beautiful specimen 

 of the A. compressa, Blain., presented to the Society by Col. 

 Thomas H. Perkins, was also exhibited ; this shell, which cost 

 him $500, is, according to Dr. Cabot, who has made the com- 

 parison, the largest Argonaut shell in any cabinet in Europe or 

 America. D'Orbigny, in his great work quoted below, gives as 

 the measurements of the largest he had examined : greatest 

 length of the shell, 9^ inches, w^hile in our specimen it is 10 

 inches ; greatest diameter of the opening 6^- inches, in our speci- 

 men it is 6^ inches ; greatest width of the opening, including the 

 auricular appendages, 3 inches, while in ours it is 4 inches. 



The animals of these three species of shells have been called 

 respectively Ocytho'e antiquorum, tuherculata, and GrancMi. Dr. 

 Gould * describes a species as A. genicidata, taken near Rio 

 Janeiro. Mr. Conrad,t in a recent monograph, besides these four 

 species, mentions the A. compressa, Blainv., from the Indian 

 Ocean ; A. papyria, Conrad ; A. gondola, Dillwyn, from the 

 South Atlantic ; A. Oweni, Adams, from the South Atlantic ; 

 A. cornuta, Conrad ; A. dispar, Conrad ; A. polita, Conrad ; 

 A. Nouryi, Lorois, from the tropical Pacific ; • A. crassicosta, 



■* Mollusca of the U. S. Exploring Expedition, p. 470. 



t Journal Acad. Nat. Sciences, Vol. 2, 1850-54, Philadelphia, p. 331. 



