58 



Tliere is a two-lobed oblong muscular scar at the back of the 

 lower edge of that of the anterior adductor. There is also a small 

 deep scar under the front of the umbones. 



Anodon i'DUCIFER. An.testd ovatd, suhventricosd, crassd, solidd; 

 antici; convexd, rotundald, postici productd, pored angulari 

 prope depressionem mnrsinis posticcc ; margine hiferiore postice 

 suhrotundatd ; disco niitdissimo, iridesccnti-margaritaceo ; perio- 

 stracft Icevi, nigra viridi radiatim pictA. 

 Hab. in fluviis Paraguaya;. 



There is only a single small ovate scar behind the lower end of 

 that of the anterior adductor muscle; the part under the umbones 

 is destitute of any. 



Mr. Gray also exhibited specimens of several Sfiells, which he 

 referred to a genus to be separated from Helix under the name of 



Nanina. 



Helix (pars), Fcr. Vitrina (pars), Quay. 



Animal. Collare amplum, lobo dcxtro antico, antro respirationis 

 in sinu posito, lobo sinistro postico lato expanso partem inferiorem 

 testae anfractus ultimi tegente. Pes postice truncatus, processu 

 brevi conico dorsali supra truncaturam sito. 



Testa depressa, perforata, polita ; apertura lunat.l ; pcristomate 

 tenui, edentulo, costa interna vel nuUfi vel obsoleta. 



Indict, China', Sfc. Jncolfe. 



The shells comprised in this genus have been referred by M. De 

 Ferussac, and by most authors, to Helix : they are, however, more 

 nearly related to Vitrina, with which M. Quoy intends placing them. 

 But from the shell of Vitrina that of Nanina differs by being um- 

 bilicated, as well as by its smaller mouth. The lobation of the collar 

 of the animal of Nanina distinguishes it also from Vitrina ; the 

 collar of the latter being entire, with a linear lobe on the side ex- 

 tending over the shell, and with the respiratory hole placed at its 

 base. 



The animal was first observed and figured by General Ilardwicke 

 in 1797. 



The following species belong to the genus: 



Nan. Nemorensis. Helix Nemorensis, Mtill, 



Nan. Javanensis. Hel. Javanensis, Fer. 



Nan. exilis. Hd. exilis, Mull. 



Nan. citrina. Hel. citrina, Linn. 

 Var. Hel. castanea, Milll. 

 Hel. Rapa, Chemn. 



Nan. monozonalis. Hel. monozonalis, Lam. 



Nan. ClairvUUa. Hel. Clairvillia, Per. 



Nan. Vitrinoides. Hel. Vitrinoides, Desk. 



Nanina Juliana. Nan. testd solidd, albd ; spird convexiusculd ; 



