BY J. c. COX. 423 



In determining the Port Jackson shell as P. octanfracta, I am 

 guided chiefly by Garrett's description and figure, as well as by a 

 careful comparison with examples from various Polynesian islands. 

 That others may form an independent opinion on the matter, I 

 add a figure, drawn for me by Mr. Hedley, and give a full descrip_ 

 tion of the shell now recorded. 



Possibly to the synonymy quoted by Garrett, viz., clausa, H. 

 and A. Adams, and consohriyia, Garrett, it will be found necessary 

 to add lirata and concinna, both of H. and A. Adams. 



Description. — Shell ovate, the periphery coincident with the 

 posterior end of the varix, rounded anteriorly, acuminate pos- 

 teriorly; colour pale purplish-brown, with a darker stripe beneath 

 the suture and a lighter band beneath that again. Whorls 7|^, 

 the upper ones together composing one-third of the shell's total 

 length, nearly flat-sided, the last sloping to the periphery, thence 

 rounded to the base. Sculpture : the body whorl encircled by 

 nineteen strong projecting revolving ridges, which cross the varix 

 and abruptly terminate at the aperture, the 

 ridges being half the breadth of the interstices ; 

 the penultimate and the antepenultimate whorls 

 have each five revolving ridges ; the earlier 

 whorls are worn smooth. Suture channelled. 

 Umbilicus funnel-shaped, about as deep as wide, 

 and about a sixth of the shell's diameter across, 



surrounded by a double rids^e which terminates 



•11 -1 11 T -IT. ^- H.,deh 



with the varix, abruptly descending, and urate 



within. Aperture one-half the length of the shell, narrow, some- 

 what ear-shaped, furnished without by a stout varix half the 

 breadth of the aperture projecting more on the anterior end, on 

 the right an inner lip stands as a riin within the varix, and spreads 

 on the left upon the body whorl as a callus which above and below 

 near each junction with the varix is emarginate, the lower emargi- 

 nation being opposite the columellar tubercle; five tubercles protect 

 the entrance; on the outer lip are two blunt bosses whose apices are 

 midway between the denticles of the left side; these latter consist 

 of a rounded tubercle on the parietal wall half-way between the 



