58 



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

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

 deep scar under the front of the umbones. 



Anodon porcifer. An.testd ovatd, subventricosd, crassd, solidd; 

 antice convexd, rotundatd, postici productd, porcd angulari 

 prope depressionem marginis posticce ; margine hiferiore postice 

 subrotundatd ; disco niiidissinio, iridesccnti-margaritaceo ; perio- 

 straca IcBvi, nigra viridi radiatim pieta. 

 Hab. in fluviis Paraguayi3e. 



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

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

 is destitute of any. 



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

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



Nanina. 



Helix (pars), Fer. Vitrina (pars), Qitoy. 



Animal. Collare amplum, lobo dextro antico, antro respirationis 

 in sinu posito, lobo sinistro postico lato expanso partem inferiorem 

 testae anfractūs ultimi tegente. Pes postice truncatus, processu 

 brevi conico dorsali supra truncaturam šito. 



Testą depressa, perforata, polita ; apertura lunata ; peristomate 

 tenai, edentulo, costa interna vel nulla vel obsoleta. 



Jndice, Chinee, S^-c. Incolce. 



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

 Fėrussac, and by most authors, to Helis : they are, hovveyer, more 

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

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

 bilicated, as vvell 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 Hardvvicke 

 in 1797. 



The following species belong to the genus : 



Nan. Nemorerisls. Helix Nemorensis, MiiU. 



Nan. Javanensis. Hel. Javanensis, Fer. 



Nan. €xilis. Hel. exilis, Mtill. 



Nan. citrina. Hel. citrina, Linn. 

 Var. Hel. castanea, Mūll. 

 Hel. Rapa, Chemn. 



Nan. monozonalis, Hel. raonozonalis, Lam. 



Nan. ClairvilUa. Hel. Clairvillia, Fer. 



Nan. Vitrinoides. Hel. Vitrinoides, Desh. 



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



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