MANGELIA. 489 



Pleurotoma gracilis, Scacchi, Catal. Test. Neapol. p. 13, f. 21, 



„ gmcile, Philippi, Moll. Sicil. vol. i. p. 198, pi. 1 1, f. 2.3. 



„ attenuatum, Philippi, Moll. Sicil. vol. ii. p. 166. 



„ aUcmiata, Reeve, Conch. Icon. vol. i. Pleurot. pi. 28, f. 248. 



This beautiful shell has a blunt subfusiform shape, and 

 tapers much and gradually to either extremity; it is rather 

 thin (for its genus), shining, not quite opaque, and adorned, 

 on a ground of pale ochre colour, with numerous rather 

 distant revolving lines of chestnut brown. In addition to 

 these markings — which are frequently absent in the young 

 — a single brown or liver-coloured narrow fillet may 

 usually be observed in the finer specimens; it runs just 

 below the extremely fine and oblique suture, but is more 

 conspicuous when continued thence across the middle of 

 the body-whorl, where it is often preceded by a rather 

 broader obscurely defined whitish or pallid band. There 

 is no spiral sculpture, but several (about nine on the final 

 volutions) strong distant more or less curved prominent 

 ribs traverse each of the principal whorls lengthways (for 

 the two or three apical ones are smooth), and extend to 

 the extreme base of the body : they become much thinner 

 below the suture. Of the eight or nine coils which com- 

 pose the shell, the body (or last formed) is about equal 

 to the rest united, and is somewhat planulate upon its 

 lower half. The whorls are rather high, of moderately 

 quick increase, and are decidedly convex (at least the 

 elevated portion) ; the apex is finely pointed. The mouth, 

 which is devoid of sculpture, occupies about one-half of the 

 entire length ; it is very narrow, and is contracted below 

 to a moderately long and straight canal. The rather 

 projecting outer lip, whose posterior sinus is very slight, is 

 thickened in the adult by the external rib. The inner lip 

 is nearly straight, and is often stained anteriorly with 



VOL. III. 'i R 



