MANUAL OF THE MOLLUSCA. 



Shell like Pileopsis, dextral as in Velletia, with a respiratory 

 channel on the right side. 



' '■Animal with the respiratory orifice on the edge of the mantle. 

 Eyes sessile at the middle of the hinder part of the base of the 

 tentacles, and are visible only from above; tentacles rather 

 conical than angular ; upper mandible conspicuous, slightly 

 lobed ; lingual ribbon broad, with 86 rows of teeth, 87 in a 

 row (43 . 1 . 43) ; they have simple obtuse hooks as in Ancylus ; 

 the central row only differs in being symmetrical ; the laterals 

 diminish gradually from the 14th to the 43rd, and a second 

 cusp makes its appearance, and increases until the three near 

 the margin are regularly bicuspid." — (Woodward.) 



The habits of C. Theobaldi are terrestrial. 



This genus is doubtfully distinct from Valenciennesia. 



Poeyia, Bourguignat, 1860. 



Dedicated to M. Poey of Havanna. 



Type, P. Grundlachioides, Cuba. 



Shell, above like Gundlachia, below like Ancylus; apex pos- 

 terior, dextral, somewhat compressed, very obtuse ; aperture 

 large, peristome simple. 



Brondelia, Bourguignat, 1860. 



The two species Ancylus Drouetianus, Bourguignat, and 

 B. gibbosa, Bourg., are terrestrial Ancyli, living on humid 

 rocks in the forest of Edough, Boue (Algeria). 



Aceochasma, Beuss, 1860. 



Type, A. tricarinatum, Eeuss, from the fresh-water limestones 

 of Bohemia. 



Shell trilateral, pyramidal, rounded below in its whole ampli- 

 tude, with one posterior concave, and two lateral slightly con- 

 vex planes, ending upwards in an acute reflected apex, beneath 

 with a longitudinal aperture through the shell, which in its 

 living state appears to have been covered with an epidermis. It 

 may be considered as a fresh- water representative of the marine 

 genus Fissurella. 



Choanomphaetjs, G-erstfeldt, 1859. 



Etymology, choanos, a funnel ; omphalos, an umbilicus. 

 Type, C. Maacki, Lake Baikal. 

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