the Caribcean Islands. 537 



Genus 4. Ceratodes. * Labro 

 simplici ; operculo corneo ; 

 testa discoidea ; umbilico 

 maximo profundo ; columel- 

 la evanida A. cornu arietis. Sow. 



Genus. Paludina. Auctorum. 



Char. Gen. 

 Animal spirale, monogenum, fluviatile, amphibium, &c. + 

 Caput proboscidiforme, liberum. Os subtus, genis tumidis. OcuH 

 prominuli, ad basin externam tentaculorum. Tentacula duo sub- 

 filiformia, subcontractilia, sinistrum in altero sexu elongatum. 

 Pes tenuis, margine antico ampliato-lobato. Solea% lata, margine 

 (serpentis) saepe reflexo. Operculum corneum, in dorso pedis. 



Testa vestita, elongato-ovata, spiralis, tenuis, subumbilicata, 

 anfractibus convexis ; apertura subsemiorbiculari, oblongiuscula, 

 superne angulat^. Peritrema |{ tenue, simplex, connexum. 



Paludina parvula. 

 Pal. flavescens, nigro irrorata; capite crasso, nigro, oculis 

 atris ; tentaculo elongate rubescente. 



* A KB^ocruioi^Sy cornu imitatus. 



+ This genus has been thoroughly investigated by the illustrious Cuvier, 

 and I have therefore less reason to regret that the minuteness of the only spe- 

 cies I have seen here prevents me from drawing up more extended characters. 



J This term may be very properly applied to the flattened disk of adhesion 

 jind motion, which is formed by the underside of the true foot (pes), and 

 which in Stenopus^ Guild., is so curiously distinguished from it, 



I It would perhaps be better to confine the term Labrum or labium to the 

 animal, using Peritrema for the outer lip of the shell, and columella for the 

 inner. The space connected with the pillar, and marked by its distinct and 

 polished outline, owing to the constant protection of the pallium, it may some- 

 times be convenient to term Columellarium. In AcJiatina undulata it is of a 

 different colour from the pillar. In some species of Cassis, by the constant 

 deposition of shelly matter, it is raised above the body of the shell. In some 

 genera it is contracted in its limits, and does not occupy, as usual, the whole 

 extent of the aperture. 



