MANGELIA. 487 



the ribs towards the base of each turn. The mouth 

 occupies from three-sevenths to one-half of the entire 

 length, and is so greatly contracted by the external rib of 

 the outer lip, as to be almost equally narrow throughout. 

 The throat is smooth, and though usually marked far 

 inwards with a reddish tawny blotch, yet towards the 

 exterior, at least, is white. The edge of the outer lip is 

 thrown back, as it were, at the arcuated posterior sinus, 

 which is quite distinct, though small, and very profoundly 

 indented ; the lip itself, which is thickened by the external 

 ribs, at first projects rather abruptly, and then slopes in- 

 ward with a gentle and continuous curvature. The pillar 

 lip is white, nearly straight, much elongated, and not very 

 broad. Half an inch for the length, and two lines for the 

 breadth, are the ordinary dimensions of mature examples. 



The cosfata proper is usually less turreted and much 

 smaller, averaging scarcely more than a quarter of an inch 

 long, though occasionally it vies (as in the elongated 

 variety, Mctcalfei) in both respects with the preceding- 

 form. The lines of colour become partially or wholly 

 confluent, so that in the more typical specimens the upper 

 part of the body is broadly banded with rufous brown, or 

 chestnut (which zone is almost always continued upon the 

 spire, whose turns frequently are wholly of the darker hue), 

 the lower half of the body being white or nearly so. There 

 are rarely more than seven and a half whorls, of which the 

 two or three apical ones are quite smooth ; usually, too, 

 they are shorter than in coarctata ; the margin of the 

 outer lip is broad, and the sinus very distinct.* 



* The P. Berlrandi of Pavraudeau (Moll. Corse, p. 144, pi. 7, f. 12, 13), 

 and the P. ccerulans of Philippi (Moll. Sicil. vol. ii. p. 168, pi. 2G, f. 4), ap- 

 proach very closely indeed to this form j but the ribs on each volution seem more 

 numerous. 



