268 FERUSSACIA, MADEIRA. 



Atlantica, 1878. I have used in the following account large 

 series of most of the species, including a set from the Lowe- 

 Wollaston collection and a series collected by Mr. Grabham. 



Key to Madeiran Species of Ferussacidse. 



a. Shell minute, fragile, very slender, whitish-corneous, with 

 straightly tapering spire and obtuse apex. 



Genus Csetilioides. 

 a 1 . Shell ovate or oblong, not as above. 



b. Outer lip straight in profile, obtuse, with a thickened 

 rim within; columella not truncate or plicate. 



Cochlicopa lubrica. 



b\ Outer lip more or less arcuate or sinuous in profile; 

 columella plicate or truncate. 



c. Whorls few, 4 to 4-J; aperture with parietal and 

 columellar lamellae and sometimes palatal folds. 



( Cylichnidia. ) 



d. Shell ovate, aperture with no palatal folds; 

 length 3.6 to 4 mm. F. ovuliformis, no. 73. 

 d 1 . Shell cylindric-oblong; a strong lower pal- 

 atal fold developed; length 2.7 to 3 mm. 



F. cylichna, no. 74. 

 c 1 . Whorls 5 to 8. 



d. Outer lip lined with a whitish callus. 



e. Outer lip in profile sloping strongly 

 forward from the suture downward; 

 aperture very narrow and acuminate 

 above. 



/. Shell about 11.5 x 5 mm. ; parietal 

 wall smooth or with a very weak 

 supraparietal thickening. 



F. melampoides, no. 63. 



f\ Shell from 9 x 4 to 6.5 x 3 mm. ; a 



rather long vertical supraparietal 



fold. F. tornatellina, no. 64. 



/ 2 . Shell narrower, about 8.5x3.1 



mm. ; supraparietal fold short and 



toothlike. F. mttriformis, no. 65. 



