28 EEV. E. BOOG WATSON OS THE 



tlie tlireadlets, but almost translucent elsewhere from the extreme 

 thinness of the shell. Apex — at the posterior end of the shell 

 there is a nai-row, roiinded, prominent beak, within which, a 

 little bent to the right and projecting slightly above the margin 

 of the mouth, is the minute apex of one whorl. IfoutTi oblong. 

 Margin minutely denticulated by the ends of the ribs ; cleft in 

 front by a strong, parallel-sided, blunt-ended fissure ; behind, it 

 is peculiarly patulous, beiug markedly bent outwards from the line 

 of attachment of the septum, this bending being strongly shown 

 on the outside of the shell. Inside glossy, smooth ; a strong 

 depression corresponding to the exterior keel extends from end 

 to end of the shell. Septum — a little way within the margin, and 

 deepest at the end, is the short oblique septum, which is faintly 

 arched, with a concave edge in front. L. 0"38. B. 0-2. H. 0'12. 

 The present species, though somewhat chipped, is of great 

 beauty. It differs from Z. calceolina, A. Ad., which is rudely 

 cancellated, and is also wider and more depressed. It is liker 

 L. reticulata, A. Ad. ; but is larger, deeper, has the old cleft-scar 

 raised on a projecting ridge which forms a strong internal furrow, 

 has the beak sharper and more projecting ; the form is more 

 oblong and more pinched-in at the sides ; the sculpture-lines are 

 much finer and less regular than in that species. 



[Since the above was in print. Prof. Seguenza has had the 

 kindness to send me a careful sketch of the solitary specimen 

 which exists of his Crepiemarginula reticulata from the Astian or 

 Middle Pliocene of Ehegium in Calabria (see ' Pormazione Terz. 

 de Eeggio-Calabria,' p. 273). It proves, as I inferred from the 

 description, to be a Zeidora ; and as in that genus reticulata is a 

 specific name already used by A. Adams, I would propose Z. Se- 

 guenzce for the Calabrian fossil. As compared with Z. naufraga, 

 this Calabrian fossil is much higher in front, much lower behind, 

 wdiere also it is much broader and rounder, with a less pinched- 

 in apex ; it is more widely ribbed, the scores on the scar are wider 

 apart and coarser ; internally the edge is more coarsely crimped, 

 and the septum is very much larger, being much more prolonged 

 forward, and is horizontal instead of oblique ; the old cleft-scar, 

 too, is not raised on a projecting ridge, and does not form any 

 internal furrow.] 



