N E R I T A. 



Plate 1. 



Genus NEHITA, Linndna. 

 Testa globoso-ovaia, spird raru exserlu, aiifractibus siibcovi- 

 presse couvolutis, interdum lamgaiis, plerumqne spira- 

 Uler costatis vel liratis, aperturd semioriicidari, labro 

 intus crenaio-lirato, interdmn ad latirra dcnticulato, 

 area colimiellari subampld, sape granulatd aid corrii- 

 gatd, ad marginem plernmqne dentatd ; colore raria, 

 sapissime vivide picta ; operculo iedaceo. 

 Shell globosely ovate, spire rarely exserted, whorls rather 

 compressly convoluted, sometimes smooth, generally 

 spirally ribbed or ridged, aperture semiorbicular, lip 

 crenately ridged within, sometimes toothed at the 

 sides, coIumcUar area rather large, often granulated 

 or wrinkled, generally toothed at the margin ; colour 

 various, mostly brightly painted ; operculum testa- 

 ceous. 

 The Sea Nerites liave always been a favourite tribe of 

 sheOs among eoUeetors, on account of their pretty varie- 

 ties of painting. The animal of the Freshwater Nerites, 

 which I propose, contrary to the opinion of some con- 

 chologists, to associate still under the head of Neritbia, is 

 the same, but the shell is of lighter structure and of more 

 sombre hue. From Natica the shell of Nerifa dill'ers in 

 being more sculptured and more brilliantly coloured, and 

 the columellar area is, with few exceptions, toothed, and 

 either grained or wrinkled. The genus has been well ex- 

 amined by M. Eecluz, but severa' of his species I have 

 been unable to identify for want );ures. Fortunately 

 the types of most of this French concliologist's species are 

 in the collection of Mr. Cuming, who confided his 'speci- 

 mens to him about fifteen years since for description. The 

 species which are named for the first time in the following 

 Monograph have accumulated since that period. 



The Nerilte are most abundant in the ^Molucca and 

 Philippine Islands, and New Zealand and Australia con- 

 tribute some fine species. A few species inhabit the shores 

 of Central America and the West Indies, but the genus is 

 not represented generally in the New World. The species 

 are less numerous than those of Neritiiia, and there are 

 few of small size. 



Species 1. (Fig. a, b, Mus. Cuming.) 

 ITA EXUVIA. Ner. testa ovald, crussd, subfm plano- 

 excavatd, spird minuld, laterali, superjiciariu, apice 



acuta, nnfract.ibus sviatigusie roiimdaiis, spiralUcr 

 costatis, codis aiigirstis, elevatis, sidcis intermediis 

 latis, conspicue excavatis, lird pared centrali percnr- 

 rente, aperturm fauce liratd, columella latissime coii- 

 caod, granulatd, ad marginem medio minute denticii- 

 latd ; costis caruleo-nigris, sparsim albo-Uneatis,mlcis 

 albidis caruleo-nigro macidatis, area colmnellari fnho 

 tinctd. 



The snake-skin Nerite. Shell ovate, thick, flatly ex- 

 cavated beueath, spire minute, lateral, superficial, 

 sharp at the apex, whorls rather narrowly rounded, 

 spirally ribbed, ribs narrow, raised, intermediate 

 grooves broad, conspicuously excavated, with a small 

 central ridge running through them, interior of the 

 aperture ridged, columella very broadly concave, gra- 

 nulated, and minutely toothed in the middle at the 

 edge ; ribs blue-black, sparingly marked with white 

 lines, grooves whitish, spotted with blue-black, colu- 

 mellar area fulvous-tinged. 



LiNX.EDS (not of Lamarck), Mus. reg. Ulricte, p. 682. 

 Ncrita Malaccensis, Lamarck. 



Hab. Philippine Islands ; Cuming. 



Much confusion has arisen through confounding the 

 well-known N. plexa of Chemnitz with the Linna'an 

 'N. exuvia; but the description " nigricans lineis transversis 

 albidis " in the careful diagnose above referred to, does 

 not apply to that species. 



Species 3. (Fig. a to d, Mus. Cuming.) 

 Xerita polita. Ner. tesid oblif/iie ovatd, subtus plano- 

 convexd, crassd, spird minutd, obtuse plunatd, anfrav- 

 tibiis angusle rotnndatis, spiram versiis lateraliter com- 

 prcssis, livvigaiis vel corriiffalo-striatis, apertura fauce 

 tix obsolete liratd, area coliimellari ad marginem rude 

 tetme dentatd ; varie iniiide eoloratd, subtus alba, po- 

 lita. 

 The polished Nerite. Shell obliquely ovate, flatly 

 convex beneath, thick, spire minute, obtusely flat- 

 tened, whorls narrowly rounded, laterally compressed 

 towards the spire, smooth or wrinkle-striated, in- 

 terior of the aperture scarcely obsoletely ridged, co- 

 lumellar area rudely finely toothed at the edge ; va- 

 riously brightly coloured, wliite and polished beueatli. 

 LiNN.n;s,'Syst. Nat. (lOlh edit.) p. 778. 



August, l!i 



