70 NERITINA. 
NECTOPO'DA. Bl. The first family of Nucleobranchiata, Bl. 
containing the genera Carinaria and Firola; the latter is not a 
shell. 
NE’MATOPODA. BI. The first class of the sub-type Malentoz- 
aria, Bl. containing all the mollusca with multivalve shells, 
except Chiton, and divided into the families Lepadicea, and 
Balanidea corresponding with Lamarck’s Sessile and Peduncu- 
lated Cirripedes. 
NEMATU’RA. Benson. Fam. Turbinacea, Lam. Deser. Thin, 
nearly oval, somewhat compressed from back to front; spire 
acute, consisting of few rounded whorls; last whorl large, but 
contracted near the aperture; aperture small, oblique, rounded 
anteriorly; peritreme continuous, thin; operculum spiral, horny, 
with few volutions. The distinguishing character of this genus 
is the contraction of the last whorl near the aperture, in which 
respect it is nearly resembled by the shell called Cyclostoma 
lucidum. Two recent and one fossil species, all very minute, 
are described by Sowerby in Loudon’s Magazine of Natural 
History, New Series. Fig. 305. 
NERI'NEA. Defr. Fam. Canalifera, Lam. Descr. Turrited, 
oblong, sub-canaliculated, consisting of numerous whorls; aper- 
ture with a strong fold on the columella, one on the outer-lip. 
and one on the inner-lip at the edge of the body whorl. Obs. 
This genus is only found in a fossil state, and is not resembled 
by any other; the strong, prominent, folds on the three upper 
angles of the sub-quadrate aperture present a singular appear- 
ance in a section. One species has been named N. Hieroglyphus. 
We give N. Goodhallii, fig. 374. 
NERITA. Lam. Fam. Neritacea, Lam. Hemicyclostomata, Bl. 
Descr. Smooth, or ribbed, semiglobose; spire short, sometimes 
flat, consisting of few volutions; aperture large, semilunar; 
outer-lip thick, entire, inner-lip thickened, dentated at the edge, 
spread over the body whorl, presenting a flattishdisc; operculum 
shelly, spiral, with an appendage, by which it is locked under 
the sharpe edge of the columella. Obs. These marine shells are 
known from Neritina, by the thickness of the shell, and the 
want of the thick horny dark coloured epidermis; from Natica, 
by the flat area produced by the thickened columella. N. Pelor- 
onta, fig. 330. N. polita, fig. 329. 
NERITA’CEA. Lam. A family of the first order of Tracheli- 
poda, containing the genera Navicella, Neritina, Nerita, and 
Natica. To which may be added several genera enumerated in 
explanation of fig. 323 to 333. 
NERITI’NA. Lam. Fam. Neritacea. Lam. Deser. Thin, semi- 
globose, obliquely oval, smooth, flattish in front; spire short, 
sometimes depressed, consisting of few rapidly increasing whorls ; 
aperture semicircular; outer-lip thin, sharp; columellar-lip 
