314 GASTROPODA. [Pectinibranchia. 



Genus 1. TONNA, Brunnich, 1772. 



Tonna, Fund. Zool., 1772, 248. Type : Buccinum galea, L. Cadu-s, Bolten, 

 1798. Dolium, Lamarck, 1801. 



Animal having the foot very large, truncated in front, attenuated 

 behind ; mantle not reflected over the shell ; tentacles cylindrical, 

 distant, eyes at their outer base on distinct pedicels ; proboscis long, 

 thick ; siphon long ; copulatory organ large, curved, with a longi- 

 tudinal groove, ending in a fleshy hook. A jaw is present. Central 

 tooth of radula with an elongated central and 2 shorter lateral cusps ; 

 lateral and marginal teeth sharp-pointed, simple. 



Shell thin, ventricose, globosely oval ; spire generally short, whorls 

 with spiral depressed ribs ; aperture very large, broadly sinuated at 

 its base ; outer lip crenulated, lirate within ; columella twisted, with 

 a fold corresponding with the basal fasciole, ending in a beak below. 



Vernacular Name. Tuns. 



1. Tonna variegata, Lamarck, 1822. Plate 47. 



Dolium variegatum, Lam., A.s.V., vii, 261 ; Dieff. N.Z., 234 ; Conch. Icon., 

 v, pi. 5, f. 7 ; Mail. Conch. (1), vii, 202, pi. 3, f. 13. D. Kienerf, Philippi, 

 Abbild. neuer Conch., iii, 36 (teste Tryon). 



Shell large, globose, spirally ribbed, umbilicate. Sculpture con- 

 sisting of low rounded spiral ribs, 15 to 18 on the last whorl, the inter- 

 stices nearly as wide, the upper ones bearing an intermediate smaller 

 rib ; the oblique growth-lines distinct and passing over the ribs. 

 Colour whitish or yellowish-brown, maculated with brown on the 

 ribs, often with one or two ribs more yellowish in colour, upon which 

 there are no maculations Epidermis thin, horny, easily peeling off. 

 Spire short, conoidal. Protoconch small, globose, of 2j smooth and 

 convex whorls, covered by a thin horny epidermis. Whorls 7, first 

 rather slowly increasing, convex, the last very large ; base rounded, 

 excavated above the fasciole. Suture excavated. Aperture large, 

 oval, sinuated below. Outer lip flatly convex, sharp, crenulated by 

 the spiral sculpture, lirate within. Columella vertical, slightly twisted, 

 with a broad low plait above, produced by the descending fasciole, a 

 few small plications further down. Inner lip spreading a little beyond 

 the columella, but leaving the narrow umbilicus open. 



Diameter, 102 mm. ; height, 120 mm. (the height varies from 

 100 mm. to 230 mm.). 



Animal unknown. 



Type in the Mus. Hist. Nat., Geneva. 



Hab. From the North Cape to T.-mnmga ; Cape Maria vari Die- 

 men (Dieft'enbach) ; Whangarei Heads (C. Cooper) ; Great Barrier 

 Island ; Tauranga (Dominion Museum). Found also in Austialia. 



Remarks. The animals live buried in muddy sand. In Australia 

 the species has been found in depths from 22 to 66 fathoms. The 



