234 CANARY ISLAND FERUSSACLE. 



much as described and figured for F. gronoviana. Formula 

 22 to 25, 5, 1, 5, 22 to 25 ; the central tooth very small, weakly 

 tricuspid, five laterals with a very long middle cusp and two 

 equal side points. The marginals from the 17th out have 

 very finely denticulate cusps. 



Species of the Canary Islands. 



The Canarian Ferussaeias are of Mediterranean type, more 

 or less related to F. folliculus. They are oblong shells with 

 weak columellar truncation, and usually a callous band with- 

 in the lip-edge, producing an external buff stripe behind the 

 lip. 



A single specimen of the Madeiran F. tornatellina has been 

 reported from Grand Canary, yet it is probably to be looked 

 upon as a chance importation, if indeed the species has actu- 

 ally obtained a Canarian foothold. Cionella webbii Mouss. 

 (Ferussacia w., Bourguignat) has been shown by Wollaston 

 to be identical with BuliminuA myosotis. F. vescoi reissi oc- 

 curs on Teneriffe. 



Our knowledge of these species is chiefly due to A. Mous- 

 son's Revision de la Faune Malacologique des Canaries, 1872, 

 and Wollaston 's Testacea Atlantica, 1878. 



17. F. VALIDA (Mousson). PL 40, fig. 39. 



Shell imperforate, 'ovate-cylindric, rather solid, very lightly 

 striatulate, very glossy, pale corneous, somewhat milky. Spire 

 long, convexly-conic, the summit minute, rather obtuse, 

 hyaline; suture linear, flat, broadly margined below. Whorls 

 6, the first nearly flat, slowly increasing, the penultimate more 

 rapidly descending, a little convex, the last whorl long, flatly 

 rounded, more convex at the base. Aperture three-eighths the 

 total length, vertical (five degrees from the axis), long-oval, 

 acute above, subangular below. Peristome straight and white 

 outside, broadly and strongly thickened within, somewhat 

 cuneate anteriorly, the margins joined by a thick lamina; 

 right margin straight above, curved below, arcuately produced 

 in front; basal a little retracted; columella straight, reaching 

 nearly to the base, obsoletely doubly thickened within. Length 

 15, diam. 5 mm. (Mouss.}. 



