AGARDHIA. 135 



Coliimellar lamella bilobed; about 15 riblets in 1 mm. 

 on face of last whorl ; diam. % the length. 



12 ^ A. macrodonta, no. 8. 

 Columellar lamella simple ; about 22 stria? in 1 mm. ; 



diam. less than % the length. A- m. gracillima, no. 8a. 



14-16 fine rib-striae in 1 mm. on face of the last whorl; 

 peristome rather broadly expanded below. 



13 <j A. rumelica, no. 9. 

 11-12 more spaced riblets in 1 mm. ; peristome narrow. 



A. t. biarmata, no. 13&. 



( Whorls distinctly flattened, the last one or two relatively 

 I long; outer lip receding strongly to the suture. 



14 ■{ A. parreyssii, no. 11. 



I Whorls somewhat convex, slowly and regularly increas- 

 [ ing (15). 



c Shell 3.6 to 4 mm- long, 6% whorls; rib-striae spaced, 

 10-12 in 1 mm. on face of last whorl; aperture tooth- 

 less or with small lamellae. A. truncatella, no. 13. 



15 <j Shell 5 to 5.5 mm. long, 8 whorls; striation finer. 



A. t. fjormosa, no. 13a. 



Shell 4 mm. long, very finely striate ; aperture toothless. 



A. t. skipetarica, no. 13c. 



Subgenus Agardhia proper- 

 The species are closely related, separated by various com- 

 binations of these characters : striation ; degree of develop- 

 ment or absence of a lip-tooth ; form of peristome ; size of the 

 palatal folds; form of base and umbilicus. Part of their 

 characters may be tabulated thus : 



(Names in italics are rib-striate species, the others smoothish.) 

 Lip-tooth present < 



' . I Parietal margin or 



olanci r ° 



, , . , peristome tree, 



valsabma J 



bourguignatiana 

 No lip-tooth i 



biplicata I Parietal margin of 



excessiva peristome adnate. 



