540 Rev. L. Guilding on the Zoology of 



Genus. Ceratodes. Guild. 

 Ampullaria. Sow. 

 Planorbis. Lam. 



Char. Gen. 



Animal Ampullarice simile, at siphones cervicis minores et 

 breviores. Penis apice supra verrucam deflexo, &c. 



Testa dextera,* discoidea, tenera, epidermide tenuissima 

 yestita, facie Planorbis, longitudinaliter plicatula ; umbilicus 

 maximus profundus, (incola serpente) sinister, centralis. Spira 

 valde depressa, vix prominula ; anfractibus omnibus dextrorsum 

 conspicuis. Operculum Ampullaria^ at reniforme. Peritrema 

 simplex, Columella evanida. Columellarium parvulum. Apertura 

 semirotundato-lunata, ab axe remotissima. 



Typus genericus, Planorbis cornu arietis +. Lam, 



Ceratodes fas ciatus. Guild. 



Cer. flavescens, nigro marmoratus : sole^ pallida, nigrescentc 

 maculata : operculo fusco, subtus castanco. 



Testa flavescente pallida, atro-castaneo fasciata : spira apice 

 rufescente, saepe corros^ : apertura crocea. 



Ampullaria cornu arietis. Sow.^ Gen, of Shells. 



Planorbis cornu arietis. Lam., vi. pars 2. p. 152. 



Lister. Conch, tab. 136. f. 40. male. 



Var. «. pulcbrior, fasciis crebris, aperturae nebula purpurea. 

 Animal pallidius, rufescente flavidum, nigro pictum, solea palli- 

 diori immaculata. 



Var. /3. fasciis paucis latioribus. 



Habitat varietate multiplici in fluviis Americae aequinoctialis, 

 satis frequens. 



Desc. Respiratorium diaphanum, amplum, fuliginosum. 

 Abdomen spirale. Cauda cinereo-livida, pallido reticulata. Pal- 

 lium pallidum, flavido reticulatum, marginis superioris glandibus 

 fasciae for mibus. Penis flavidus. 



* The shell, when placed with the spire upwards, will not warrant us in 

 calling it, with Lamarck, a sinistral species. 

 + Nomina composita vituperauda, expellenda. 



