324 PEOCEKDINGS OF THE MALACOF-OGICAL SOCIETY. 



crenellated and serrated by the termination of the groups of frill-like 

 costulae ; perforation very narrow, spinously costulate ; peristome 

 continuous, subcircular, outwardly frilled by the termination of the 

 spiral lirse except in the immediate contra-parietal region; operculum 

 calcareous, sinistral, white, deeply depressed in the centre, having four 

 volutions, the two outer whorls closely, obliquely, arcuately costulate, 

 the two inner bearing an erect, serrated, spiral ridge. Alt. (allowing 

 for apical whorls), 8'75 (about), diam. maj. 4 mm. ; aperture, 

 alt. 1-75, diam. 1-75 mm. 



Hah. — Bayate, near Concepcioncita, 30 miles north-west of 

 Guantanamo, "a totally unexplored locality" (C. T. Kamsden). 

 Young specimens of this extraordinary form are widely umbilicate 

 and bear a marginal, a sub-marginal, and an interior spiral liration. 



