pulmonata. 63 



1. Mari^lla Dussumieri. B.M. 



Foot produced behind, keeled, truncated with a double edge. 

 Mantle shield-like, free in front, convex, and separated behind 

 by a distinct groove from the front ])art of the back of the foot ; 

 smooth above, with three slight keels on the hinder part, the 

 central one the longest and most distinct. Back without the 

 least appearance of a hole. Back of the neck with three grooves, 

 central double, lateral diverging to the hinder part of the side of 

 the head. 



Shell completely hidden, half ovate, elongate, solid, white, 

 with a thin narrow corneous margin ; apex subtenninal on the 

 right hinder edge, internally horny, only slightly concave. 



" Clypeidella Dussumieri, Valeric. MSS." French collection 



purchased in London. 

 Hab. Mahi, near Sechelles {M. Dussumier). 



b. Body and shell subglobose, distinctly spiral. 

 * Shell entirely and permanently covered with the mantle. 



6. LACONIA. 



Shell subglobose, entirely and permanently covered with a tliin 

 expansion of the mantle. Spire of few whorls, last very large. 

 Aperture very large, lunate. Mantle edged, produced in front, 

 forming a broad collar. 



1. Laconia Ferussaci. 



Vitrina, sp. ? Desh. in Ferussac Hist. Moll. t. 8 F. f. 10, 11. 



Gray, Fig. Moll. i. 286. f. 3. 

 Hab. Unknown. 



Only known by Ferussac's figure. 



** Shell permanently covered by the thin reflexed edge of the 

 mantle, leaving the central portion more or less exposed. 



7. PARMACELLUS. 



Shell subglobose, spiral, partly and permanently covered by the 

 mantle ; the front of the mantle rather produced, forming a small 

 fleshy collar ; the hinder part rather convex. 



