424 GASTROPODA. [Pectinibranchia. 



towards the canal, where it ends in a straight and rounded ridge. 

 Inner Up broad, polished, forming a thick callosity on the parietal 

 wall, broadly expanded, and with a rounded edge towards the depres- 

 sion below the fasciole. Operculum ovate-triangular, dark brown, 

 with the nucleus lateral. 



Diameter, 42 mm. ; height, 64 mm. Diameter, 73 mm. ; height. 

 118mm. (large specimen). 



Animal having a large dilated oval foot, brownish-white on the 

 sides, sole yellowish-white ; tentacles thick, short, and conical, vio- 

 laceous brown, eyes near the extremity. 



Dentition (Button, T.N.Z.I., xv, 120, pi. 13, f. P). Central tooth 

 with 3 long triangular cusps, the median of which is the largest. 



Type lost. 



Hab. North Island ; Cook Strait ; Nelson. Brought to England 

 by Captain Cook. Also Tasmania. Australia. Lord Howe Island, Cape 

 of Good Hope. 



Fossil in the Pliocene. 



Remarks. This species is very variable in size and sculpture, 

 all intermediate varieties between succincta and textiliosa being met 

 with ; the finer ornamented form, however, is much more common. 

 The nature of their habitat is most likely influencing the sculpture 

 to some extent. These molluscs are mostly found in clusters of about 

 half a dozen together, in crevices of rocks near low-water mark. 



Maori. Tawiri (fide Captain Bollons). 



3. Thais tritoniformis, Blainville, 1833. Plate 45, fig. 19. 



Purpura trilonifonnis, Blaiiiv., Nouv. Ann. du Mus., i, 1833, 221, pi. 10, 

 f. 10 ; Kiener, Icon'. Coq. Viv., Purpura, 1836, 37, pi. 8, f. 18 : Kesteven, 

 P.L.S. N.S.W., xxvi, 1902, 533, pi. 29 ; Hedley, Mem. A.M., iv, 384 ; 

 Index, 72. Cominella (Agnewia) tritoniformis, Blainv. : Pritckard and 

 Gatliff, P.R.S. Vic., x (n.s.), 275. C. typica, Dunker, P.Z.S., 1856, 

 357. Adainsia typica, Angas, P.Z.S., 1867, 192. Agnewia typica, Dkr. : 

 T.-Woods, P.R.S. Tas., 29. Cominella (Adamsia) typica, Dkr. : C'hall. 

 Rep., xv, 214. Urosalpinx tritoniformis, Blainv., Man. Conch. (1), ii, 

 156, pi. 39, f. 491. 



Shell small, fusiform, rather thin, axially costate and spirally 

 finely lirate, fulvous, often with dark bands. Sculpture consisting of 

 numerous equidistant rounded and sometimes nodulous axial ribs, 

 extending over the base, about 12 on a whorl,- the interstices of 

 about the same width as the ribs ; crossed by very numerous close 

 inequidistant spiral threads, passing over the ribs, mostly 2 to 4 closer 

 together, leaving only one cord in the interspace ; on the base they 

 are sometimes stronger and more equidistant, ornamenting also the 

 very distinct fasciole. Colour yellowish-brown, with narrow dark- 

 brown spiral bands, 3 on the penultimate and 6 to 8 on the body 

 whorl ; aperture yellowish-white inside, occasionally banded with 

 brown. Spire elevated conic, slightly turreted, about the same height 



