371 



Blainville, from Australian Seas ; and A. naviformis, Conrad. 

 A specimen of A. JVouri/i, obtained from Dr. J. C. Parkinson, of 

 New Jersey, was exliibited from Dr. Warren's collection, an 

 extremely delicate and beautiful shell. 



The principal internal organs were described, illustrated by 

 colored, enlarged, and beautiful drawings. 



The mantle is thick and fleshy, and adheres to the head pos- 

 teriorly, having a single anterior opening. The arms are eight 

 in number, attached to the cephalic cartilage, the first pair 

 being dilated and membranous at the extremity ; all are pro- 

 vided with two rows of sessile unarmed acetabular or suctorial 

 disks, for purposes of prehension. In an animal from the Gulf 

 of Guinea, described by Dr. W. E. Leach * under the name of 

 Ocythoe Gra7ichii, (the animal of Argonauta Mans,) it is stated 

 that these membranes are generally attached to the sides of the 

 arms, but in one specimen the membranes adhered only by their 

 base below the apex of the arm ; the membrane is subject to 

 great variation in size and form, and is often different on the 

 arms of the same individual. The suckers on the palmated arras 

 extend round the whole circumference of the part, visible to the 

 naked eye ; hence Owen says t it appears as if this characteristic 

 structure arose from the extremities being bent back on them- 

 selves and united to the stem by means of a thin membrane. 



Having no fins to the mantle, like the Decapods, it must chiefly 

 progress, while swimming, in a retrograde manner by ejecting 

 water from its funnel. The expanded extremities of the dorsal 

 arms, which poets have celebrated as being kept erect to catch 

 the breeze, + cannot be regarded as such by the naturalist ; for in 

 some Octopi, according to Owen,§ similar membranes are found, 



* Phil. Trans. Vol. 107, 1817, pp. 295-6, London, 

 t Trans, of Zoological Society, London, Vol. 2, pp. 113-119, 1837. 

 X Aristotle, JElian, Oppian, Atheneeus, Pliny, and other Greek and Latin 

 authors, have written both in prose and poetry of this little navigator, which 

 they considered as a special favorite of the Gods, and as the instructor of man 

 in the art of navigation. Modern poets have also sung its praises — among 

 others, Pope and Byron ; the former writes : — 



" Learn of the little Nautilus to sail, 



Spread the thin oar, and catch the driving gale." 



§ Cyclopedia of Anat. and Phys. Art. Cephalopoda, London, 183G. 



