278 



Subgenus C(ELOTROCHUS, Fischer. 



[Coq. Viv. 1880, p. 417.] 



False umbilicus deep and narrow ; the columella is inserted to 

 one side instead of in the centre of the axis of the shell. 

 Tijfe. — Trochus tiaratus, Quoy and Gaimard. 



Trochus (Coelotrochus) tiaratUS, Quoy and Gaimard. 



1834. Trochus tiaratus, Quoy and Gaimard, Voy. de I'Astrolabe, Zool. 



t. iii, p. 2j6, pi. Ixiv. figs. 6-11. 

 183.5. Pohjodonta elegans, Gray, Yate's Account of New Zealand, p. 309. 

 1846. Trochus delicatulus, Philippi, Zeitschr. fiir Malac. p. 10.5. 

 1873. Trochus [Polydonta) tiaratus. Von Martens, List. Moll. N.Z. p. 32. 

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

 1873. Polydonta tiarata, Hutton, Cat. Tert. Moll. N.Z. p. 15. 

 1880. Anthora tiarata, Hutton, Man. N.Z. Moll. p. 94. 

 1880. Coelotrochus tiaratus, Fischer, Coq. Viv. p. 417. 

 1889. Trochus {Coelotrochus) tiaratus, Pilsbry, Tryon's Manual of Concliology, 



vol. xi. p. 42, pi. xii. figs. 72-4. 

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



p. 68. 



This well-known species differs from T. vtridis in being broader, 

 less granose, by having a deeply-cut suture, the base is less concave, 

 and by the absence of small tubercles on the inner margin of the 

 aperture. It is specially characterized by the nature of the false 

 umbilicus, which is plain and deep ; by the possession of a broad 

 simple surface on and near the columellar border ; by a rim and 

 tooth-like thickening on the posterior of the inner margin ; and 

 by the comparatively flat base, which is spirally granulate. 



Dimensions. — Length 14 mm.; breadth 15 mm. 



Form, and Loc. — Pliocene : Wanganui, New Zealand. 



G. 9568. An example of the adult. Sir James Sector Coll. 



Trochus, sp. 



6. 9572. Cast of a new species, too imperfect for detailed 

 description. The spire is much elevated ; whorls distantly 

 tuberculose ; last whorl keeled ; base flat. Eocene : Trelissick, 

 New Zealand. Sir James Hector Coll. 



