304 GASTROPODA. [Pectinibranchia. 



of 2 or 3. Columella subvertical, faintly concave above, convex 

 below. Inner lip produced far beyond the columella as a free plate, 

 narrowed to a point below ; spreading as a thin polished glaze widely 

 upon the body-whorl, with a prominent fold above, usually 2 smaller 

 ones below it ; columellar border with numerous folds, stronger and 

 more raised below. Sometimes an umbilical chink is present. Oper- 

 culum thick, horny, dark brown, concentrically lamellate, nucleus 

 apical. 



Diameter, 9-5 cm. ; height, 20 cm. (large specimen). 



Dentition. Troschel, Das Gebiss d. Schnecken, pi. 19, f. 11 a, b\ 

 Man. Conch. (1), iii, pi. 2, f. 5 ; Atlas, pi. 1, f. 3. 



Hob. North Island, as far as Napier and Kawhia ; Chatham 

 Islands. Mediterranean, Atlantic coast of Europe, British Channel, 

 Canaries, Japan, Australasia. 



2. Septa tritonis, Linnaeus, 1758. Plate 42, fig. 1. 



Murex tritonis, L., Syst. Nat., ed. x, 754. Tritonium tritonis, L., Ad. G.R.M., 

 pi. 11, f. Ic. Triton tritonis, L., Man. Conch. (1), iii, 9, pi. 1, f. 1 ; pi. 3, 

 f. IB ; pi. 5, f. 25. T. variegatum, Lamarck, A.s.V., vii, 1822, 178 ; 

 Conch. Icon., ii, pi. 2, f. 3, 6. Lotorium tritonis, L., Index, 75. 



Shell very large, fusiform, solid, with broad flat spiral ribs, yellowish, 

 variegated with brown. Sculpture consisting of broad flatly convex 

 spiral ribs, about twice as broad as the interstices, which are orna- 

 mented with 1 or several smaller cinguli ; the whorls are usually 

 slightly shouldered, and the shoulder bears 4 narrow rounded spiral 

 ribs, slightly nodulous, the uppermost broader than the others, and 

 margining the suture ; on the earlier whorls the spiral riblets, 3 to 4 

 on a whorl, are narrow, distant, and distinctly nodular. The varices 

 descend in the same direction on alternate whorls ; they are thick and 

 rounded on the upper whorls, sharp and foliaceous on the last two 

 whorls. Colour whitish or yellowish, variegated with semilunar mark- 

 ings of dark brown arranged in axial rows ; inside of aperture deep 

 orange, with double revolving reddish-brown bands ; the columella 

 banded with white and dark brown. Spire elevated, conic, mostly 

 somewhat higher than the aperture. Protoconch lost in most speci- 

 mens, very likely of a few smooth convex whorls. Whorls about 9-12, 

 the last very large, depressed convex ; base rounded, concave above 

 the short canal. Suture impressed, uneven, wavy. Aperture very 

 large, slightly oblique, ovated, channelled above, produced below into 

 an open, broad and short, recurved canal. Outer lip expanded, sharp, 

 denticulated at the margin, each denticle ending a double revolving 

 brown band. Columella vertical, arcuate. Inner Up extending be- 

 yond the columella as a free plate, forming a deep false umbilicus 

 above and a deep oval fissure below ; the lip is spreading over the 

 parietal wall, and is crossed throughout by numerous irregular white 

 wrinkles or plaits. 



Diameter, 18 cm. ; height, 38 cm. Angle of spire, 40. 



