

NAUCLEA NECROBIA. 



Banlbusa lalifolia by Humboldt and Bonplanii, but 

 made a separate genus by Jussieu. 



NAUCLEA (Linnaeus). An East Indian genus 

 of trees and shrubs, belonging to Pentandria and to 

 the natural order Rubiacecc. Generic character : 

 flowers in a close head ; calyx of five teeth persist- 

 ing; corolla funnel-shaped, elongated ; limb five-cleft; 

 anthers almost sitting, and inserted into the sinus of 

 the limb ; style long and protruding ; stigma headed. 

 Fruit drupaceous, united in a double berry ; berries 

 many-seeded. These are store plants, and succeed 

 and are increased in the ordinary way. 



NAUCORIS (Geoffroy). A genus of aquatic 

 hemipterous insects belonging to subsection Hydro- 

 corisa, and family Nepidae, having the body of an oval 

 subdepressed form, without any terminal filaments; 

 the antennae minute and four-jointed ; the fore legs 

 raptorial, and the four hind legs ciliated and well 

 adapted for swimming; the posterior tarsi two-jointed, 

 and with two ungues. There is but a single British 

 species, Nepa cimicordcs (LinnaBus), which is about 

 half an inch long, of a greenish-brown colour, with 

 the head and thorax brighter coloured. It is of com- 

 mon occurrence in ponds and stagnant waters ; is very 

 active, and well fitted for preying upon other aquatic 

 insects, its beak being short and robust. 



NAUTILUS (Linnaeus, Lamarck). This very 

 elegant mollusc is so generally well known to every 

 collector of shells, that a very detailed description 

 would be superfluous. Its form is spiral, discoid, 

 the whorls contiguous, the last enveloping the others ; 

 numerous cells, separated by a thin pearly partition, 

 or transverse septum, concave on one side, and per- 

 forated by a syphon running through them all. Some 

 species are urnbilicated, but none are known to be 

 mammilated. In the fossil species the divisions of 

 the cells form external ruts, and assume a great 

 variety of sculpture ; but in the recent species these 

 divisions are but slightly visible ; and when the shell 

 is divested of its exterior coating, and the pearly sub- 

 stance displayed, no trace of these separations can 

 be discovered. The animal inhabiting this mollusc 

 only occupies the last open division of its shell, being 

 attached to it by means of a tendinous or muscular 

 appendage, which passes into the syphon ; the mantle 

 is obliquely opened, and prolonged into a kind of 

 hood above the head, which is provided with ten- 

 tacular appendages, as if digitated, and surrounding 

 the aperture of the mouth. In the fossil genera of 

 the Nautilacce two syphons are found to penetrate 

 the cells, but we do not know of any living species 

 presenting more than one. This mollusc, from its 

 graceful form, and the beautiful prismatic pearly 

 appearance it exhibits when the external coloured 

 coating is carefully taken off, has been known to 

 naturalists from the earliest period. Artists have 

 exercised their graphic skill in ornamenting it with 

 landscapes, historical and mythological engraved sub- 

 jects ; and in the accounts given of some of the costly 

 articles of regal splendour, we read of these shells 

 being mounted, as drinking cups, in gold, bedecked 

 with jewels. In our times specimens of the Nautilus, 

 thus exquisitely fashioned, have sold at high prices, 

 and are to be seen in the cabinets of the wealthy 

 amateurs of the fine arts. Much speculation of opinion 

 exists as to the habits of this mollusc, which ig 

 described as sailing before the wind like a vessel ; 

 and it is by some conjectured that the empty cells 

 contain air or water, which the animal can volun- 



tarily expel, so as to render its habitation sufficiently 

 buoyant to rise to the surface of the waters. Other 

 naturalists are of opinion that the shell is nearly 

 enveloped in the mantle, and the animal carries it ou 

 its back in the manner of the snail, crawling habi- 

 tually at the bottom of the sea, which it only quits 

 from peculiar circumstances of necessity or conve- 

 nience. The late lamented Mr. Bennet captured 

 one of these animals attached to its shell ; and that 

 eminently talented zoologist, Professor Owen, has 

 published a most elaborate and. interesting description 

 of its structure, which we will not mutilate by partial 

 extracts. A singular part of its formation is what has 

 been termed the beak, that is, a hard portion resem- 

 bling the parrot's beak, by means of which this 

 mollusc possesses the faculty of crushing smaller 

 shells, Crustacea, &c., indicating its being carnivo- 

 rous. A transverse section of this shell exhibits one 

 of the most beautiful examples of nature's mathe- 

 matical symmetry that can be witnessed ; and en 

 passant we will take this opportunity of suggesting 

 the propriety of sectional specimens of the genera of 

 molluscs, to exhibit more fully their structure. The 

 author of this article has many specimens, but there 

 is no complete series. Where they should be found, 

 the British Museum, they (like many other things 

 necessary to science) are not, and the department of 

 malacology is there an instance of " confusion worse 

 confounded." Under the article AMMONITES, the 

 fossil gigantic species of a former creation are 

 described. 



NAVICELLA (Lamarck; NEHITA, Chemnitz). 

 These molluscs are nearly allied to the genus Nerita, 

 but yet more closely to the Neritina. They are flu- 

 viatile or fresh-water shells. The summit does not 

 turn in an oblique spiral curve, as in the genera 

 mentioned to which they are allied ; it is straight, 

 turned quite to the base, and concave beneath ; the 

 left margin flattened, sharp, and straight, forming a 

 flat internal partition resembling a haif-decked boat, 

 though this does not ever cover half the aperture of 

 the shell ; it has an epidermis, and is closed by a 

 solid, flat, thin calcareous operculum, with one lateral 

 and subulate tooth or apophyse. Their habitat is in 

 the Indian Archipelago, and the animal is carefully 

 figured in the Zoological Atlas to the Voyage de 

 PUranie. This mollusc is classed in the fourth family 

 Henricyclostoma, second order Asiphonobranchiata, se- 

 cond class Paracephalophora. 



NEBRIA (Latreille). A genus of coleopterous 

 insects belonging to the family Carabidee and sub- 

 family Cat-abides, having the body of an oval-oblong' 

 and flattened form ; the thorax cordate truncate, the 

 palpi short ; the mandibles not dilated externally, as in 

 I.eistus; the body generally furnished with wings, and 

 the three basal joints of the anterior tarsi dilated in 

 the males. These are handsome terrestrial insects 

 generally found on the sea-coast ; the type being the 

 X. complanata, of a butt' or clay colour, with black 

 markings. Dr. Leach has separated some species 

 under the name of Hclubia, including the very com- 

 mon Carabus brevicoltis of Fabricius ; whilst Bonelli 

 has detached the apterous species, which he has 

 named Alpeeus. 



NECROBIA (Latreille). A genus of coleopte- 

 rous insects, belonging to the family Cierida;, having 

 the antennae terminated by a three-jointed club, of 

 which the joints are not closely fixed together ; the 

 lour palpi arc terminated by an enlarged triangular 



