GASTROPODA. [Aspidobranchia. 



dinally marked with numerous narrow regularly spaced olive lines, 

 the first whorls often bright-orange coloured. Spire conic, sides 

 convex. Protoconch small, conical, consisting of 3 smooth convex 

 whorls. Whorls 5, convex, the last subangled at the periphery ; base 

 flatly convex. Suture linear. Aperture oblique, iridescent and lirate 

 within. Outer lip convex, sharp, narrowly edged with black, followed 

 by a white opaque band. Columella oblique, arcuate, not very thick, 

 white-edged, obtusely dentate below. Umbilicus partly covered ; 

 umbilico-columellar area bright green. 



Diameter, 16-18 mm. ; height, 17 mm. 



Dentition unknown. 



Type of the T. mimetica in the Otago Museum, Dunedin. 



Hab.Qu Zostera beds in Auckland Harbour ; scarce (T. F. Cheese- 

 -tnan). Australian coasts. 



Genus 3. CANTHARIDUS, Montfort, 1810. 



Cantharidus, Mft., Conch. Syst., ii, 1810, 251. Type : Limax opalus, 

 Martyn. Cantharis, Fer. Elenchits, Swainson, Treat. Mai., 1840, 351. 



Animal having the eye-bearing peduncles long and the tentacles 

 ciliiform ; there are 3 pairs of epipodial cirri ; the foot is short, obtuse 

 behind. Formula of teeth of radula oo 5 + 1 + 5 co. The central 

 tooth has a body with broadly expanded supporting-wings, a narrowed 

 neck, which bears a simple cusp ; this peduncle has on each side 

 delicate wings, identical with those found in several species of Gibbula. 

 The lateral teeth, 5 on each side, increase in size from the inner to the 

 outer one ; this peculiarity, together with that of the central tooth, 

 will enable one to recognise a radula of this genus at a glance. The 

 inner lateral is slender, narrowed toward the cusp, like the centrals, 

 and sometimes bearing a lamella behind the peduncle. The outer 

 laterals are very broad, with one or several denticles on the cusp. 

 There are no jaws. 



Shell ovate-conic or pyramidal, irnperforate, smooth or spirally 

 sculptured outside, brillantly iridescent within ; colours generally 

 bright and variegated ; aperture less than half the length of the shell, 

 longer than wide, ovate ; columella usually more or less folded or 

 toothed near the base. 







Distribution. Australasian seas. 



Fossil in the Pliocene. 



This genus is also Indo- Australian, like Trochus. 



Subgen. 1. CANTHARIDUS, Montfort. 

 Sect. 1. CANTHARIDUS, s. str. 



Shell rather thin, ovate-pointed, whorls striated or smooth ; colu- 

 mella rather straight, simple, not toothed. 



