277 



terminated by a dentiform projection or a small plication; anterior 

 of the columella, or basal border, often plicate or deiitate. 

 Type. — Trochus niloticus, Linnajus. 



Subgenus ANTHORA, Gray. 

 [Guide Syst. Dist. Moll. 1857, p. 148.] 



False umbilicus shallow, carrying two costae on the inside ; 

 columella oblique, with a small fold or dentiform plication 

 posteriorly, otherwise simple. 



Type. — Polydonta tulerculata, Gray. 



Trochus (Anthora) viridis, Gmelin. 



1790. Trochus viridis, Gmelin, Linn. Syst. Nat. ed. 13, p. 3572. 



1843. Polydonta tuberculata, Gray, Dieffenbach, Travels in New Zealand, 



p. 239. 

 1852. Trochus aciuosus, Gould, U.S. Espl. Exped. p. 179. 



1854. Trochus fulvolabris, Hombron and Jacquinot, Voy. au Pole Sud, 



Zool. t. V. p. 56, pi. xiv. figs. 14-16. 



1855. Pobjdonta tritonis, A. Adams, Proc. Zool. Soc. p. 132. 



1873. Trochus [Polydonta) tuberculatus, Von Martens, List. Moll. N.Z. 



p. 32. 

 1873. Polydonta tuberculata, Hutton, Cat. Marine Moll. N.Z. p. 36. 

 1880. Anthora tuberculata, Hutton, Man. N.Z. Moll. p. 93. 

 1889. Trochus [Anthora) viridis, Pilsbry, Tryon's Manual of Concbology, 



vol. xi. p. 43, pi. iii. figs. 16, 17. 

 1893. Trochus viridis, Hutton, Linn. Soc. N.S."W., Macleay Mem. Vol. 



p. 68. 



Shell conical, solid ; whorls having five or six closely - set 

 rows of bold spiral granulations, the one nearest the suture 

 posteriorly being rather larger than the others, which are 

 approximately equal in size ; base flat, concave, spirally striated ; 

 aperture quadrate, nacreous ; outer margin very oblique, Urate 

 ■within ; inner margin tuberculose ; false umbilicus shallow, 

 furnished with spiral ribs. 



Dimensions. — Length 23 mm. ; breadth 20 mm. 



Form, and Loc. — Post-Pliocene : Turanganui, Poverty Bay, New 

 Zealand. 



G. 9569. Two examples of the adult. Sir James Hector Coll. 



