PNEUMONOPOMA. 183 



fente ombilicale. Spire acuminee, aigue. Cinq tours un peu con- 

 vexes, clont le dernier surpasse le tiers de la longueur totale. Ouver- 

 ture peu oblique, oblongue ; paroi aperturale munie, vers le milieu? 

 d'une seule denticulation assez forte. Peristome legerement borde 

 et assez reflechi. Bord exte"rieur inflechi en dedans. 



Long. If de mill. ; diam. f mill. 



Habite les Etats-Unis d'Amerique. 



Le Carychium euphceum peut etre rapproche des Carychium ex- 

 istelium et exiguum. 



1. On le distinguera de Yexistelium a sa taille plus faible, a sa 

 spire plus aigue, a son ouverture proportionellement plus dilatee, a 

 sa paroi aperturale ornee, vers son milieu, d'une petite denticula- 

 tion ; a son peristome plus reflechi et plus epaissi, etc. ; enfin a ses 

 cinq tours de spire, etc. etc. 



2. On le separera de Vexiguum a sa taille egalement plus faible, 

 a son ouverture munie seulement d'une seule denticulation, tandis 

 que celle de Vexiguum en possede deux, a son peristome plus epaissi, 

 plus reflechi, a sa spire plus aigue, etc. etc. 



SPURIOUS SPECIES. 



Carychium armigera, contracta, and rupicola of Say (1. c.) are now 

 ascertained to be true Pupce, as he suggested they might be ; as 

 is also Carychium corticaria Ferussac, (Tabl. Syst.) 



PNE UMONOP OMA. 



The above named order includes all the following fami- 

 lies. The animals which compose it are distinguished 

 from those of the preceding families of Limacea^ Helicea, 

 and Auriculacea, by the presence of an operculum, which 

 is affixed to the foot and covers the aperture of the shell 

 when they are withdrawn in it. They are terrestrial, 

 breathing air by means of organs analogous to lungs. 

 They are also unisexual, and have but two contractile 

 instead of retractile tentacles, at the base of which are 

 situated two eyes. The mantle is sometimes, though not 

 always, free. 



