Page:The American Cyclopædia (1879) Volume XII.djvu/185

 NAUTILUS NAUVOO irr shaped elevations on the convex surface. The paper nautilus or argonaut belongs to the oc- topod group of the dibranchiate cephalopods, or to the acetabulifera of D'Orbigny, from the arms being provided with sucking disks. It differs from the true nautilus in the arms of larger size and more complicated structure, partially connected by membrane at the base ; in the larger and more complex eyes, not pe- dunculated but lodged in orbits; in the gills being only two in number, each with a bran- chial heart ; in the funnel being an entire tube ; and in the presence of an ink gland and bag for its secretion. In the genus argonauta (Linn.), in the females, which alone have a shell as an egg receptacle, the first or dorsal pair of the eight arms are dilated into broad thin mem- branes, which secrete and sustain the very light, paper-like, calcareous, symmetrical, and single-chambered shell; like the other arms, these are provided with two rows of suctorial disks, extending around the whole circumfer- ence, by means of which the animal retains the shell in position; the six non-palmated arms serve as organs of prehension and loco- motion, as the animal drags itself along the bottom or climbs the rocks in search of food, and as anchors ; the shell, as in the nautilus, is carried above the body. The arms are at- tached to the anterior part of the cephalic car- tilage; the suckers are completely under the control of the animal, which can fasten or relax them instantly. Swimming is effected in a retrograde manner by the ejected currents from the funnel. The skin is soft and tender, and includes a great number of cells contain- ing pigment matter of different colors, whose contractions and expansions, with the surface movements, give it a remarkable power of rap- idly changing its tints. There is no internal shell, and it is now ascertained that the exter- nal shell is peculiar to the female, and is only an incubating and protective nest for the eggs ; it is not the homologue of the internal rudi- mentary shell of the cuttle fish, nor of the external chambered shell of the nautilus, but rather answers to the cocoon of leeches and other articulates, or to the egg-float of the delicate gasteropod janthina ; the eggs are attached by thread-like stalks to the involuted Paper Nautilus (Argonauta argo). spire of the shell, behind and beneath the body of the female. The best known species, the A. argo (Linn.), inhabits the Atlantic, Pacific, and Indian oceans, and the Mediterranean, especially about Sicily. In the last named lo- cality Mme. Jeanette Power made the experi- ments which determined that the argonaut is the maker of its own shell, and not a parasitic occupant like the hermit crab ; this question arose from the fact that the animal has no muscular or other attachment to the shell, and has been known voluntarily to quit it, and sur- vive in captivity a considerable time without any attempt to return to it ; it also repairs the shell when broken by the agency of the pal- mated arms. For an account of the arguments for and against parasitism (among the advo- cates of the former being Lamarck, Leach, De Blainville, Broderip, and Sowerby, and among those of the latter Cuvier, Duvernoy, Fe>ussac, and D'Orbigny), and for an extensive bibli- ography on this animal, see "Proceedings of the Boston Society of Natural History," vol. v., pp. 369-'81 (1856). Leach, who considered the animal a parasite, described it as the genus ocythoe. The sexes are distinct ; the specimens usually found are all females, the males hav- ving been until recently described as parasites under the name of hectocotylus ; this is a worm- like body, resembling the arm of a cuttle fish, the under surface bordered with 40 or 50 pairs of alternating suckers ; for a long time regard- ed as a parasitic annelid, it is now known to be the spermatophorous arm of the male argo- naut, deciduous during sexual congress, and attaching itself within the mantle of the fe- male ; in this genus it is the third arm of the left side which is thus deciduous and hollowed for the spermatic receptacle. The male argo- naut has no shell and no palmated arms, and is only about* one eighth of the size of the fe- male. The argonaut, according to Rang, rises to the surface shell upward, turning it down- ward when it floats on the water ; by retract- ing the six arms within the shell and placing the palmated ones on the outside, it can quick- ly sink, explaining why the animal is so rarely taken with the shell. The shell is flexible in the water, but very fragile when dry; after having been soaked in water for some time it may be bent as before. A specimen, one of the largest known, in the cabinet of the Boston society of natural history, is 10 in. long, 6 broad, and the opening 4 in. wide ; it cost the donor $500. Many species are described. NAFVOO, a township of Hancock co., Illinois, on a bend of the Mississippi river, near the head of the lower rapids, 52 m. above Quincy and 220 m. above St. Louis; pop. in 1870, 1,578. The city of Nauvoo was founded by the Mormons in 1840, and contained about 15,000 inhabitants at the time of their expul- sion in 1846 by the neighboring people. It was regularly laid out with broad streets cross- ing at right angles, and the houses were built generally of logs, with a few frame and brick buildings interspersed. A temple 130 ft. long by 90 wide was erected of polished limestone. The baptistery was in the basement, and held a large stone basin supported by 12 colossal oxen. In 1848 this building was set on fire by an incendiary, and all destroyed except the