280 Rev. R. T. Lowe on the genera 



Art. XXXIX. On the Genera 3Iehimpus, Pedipes and 

 Truncatella: ivith Ea-perhnents tending to dononstrate 

 the real nature of the Respiratory Organs in these Mol- 

 lusca. By the Rev. R. T. Lowe, B.A. 



Class. Gasteropoda. 



Order. Pectinibranchia. 



Fam. PlicacEjE. (Les Plicacees, Lam., excl. Tornatella.) 



Gen. Melampus, Montf.; Les Melampes, Cnv.; Conomlus, 

 Lam.; Auriculae pars, Ejusd., Syst., et Feruss.; Volutae species, Linn., 

 Montag., Donov., Turt. 



Tentacula (2 contractilia) annulata, subcylindrica, obtusa, basi dis- 

 tincta ; oculis sessilibus, paullo supra basis angulura internum positis. 

 Caput infra tentacula porrectum, sc. ante eorum basin deorsum spectans ; 

 buccis labialibus utrinque magnis, dilatatis, antic^ coalitis, depressis, 

 horizontalibus, discum latum, bilobum, quasi pedis partem anticam, for- 

 mantibus. Os subtus ad emarginationem in medio disci hujusce labialis ; 

 simplex (ut in Helice,J sc. maxilla cornea, lunata, superiore ; inferiore 

 nulla. Pes simplex brevis ovalis antic^ obtusissimus, vix truncatus ; 

 postice subattenuatus, obtusus. Pallium collare fie Collier, Fferuss.) 

 tumidura, siphone nullo ; orificio respirationis vel ani postico ad dextrura 

 corporis, ut in Helice. Operculum nullum. 



Testa solida, subconiformis, laevigata, plerumque non sculpta, unicolor, 

 vel spiraliter obscure subfasciata. Spira breviuscula. Columella plicata. 

 Labrum simplex, superne integrum, in collumellam desinens, postice 

 vel inferne subsinuatum.* 

 Epidermis nulla. 



Animal littorale, amphibium, sed rcvera marinum, et hranchiis spirans. 

 The genus Melampus was formed by Denys de Montfort for the recep- 

 tion of the Bulimus coniformis of Bruguiere. Lamarck had also once 



• This slight notch corresponds to the situation of the respiratory or anal 

 orifice in the mantle. 



