282 GASTROPODA. [Pectinibranchia. 



Genus HIPPONIX, Defrance, 1819. 



Hipponix, Defrance, Bull. Soc. Philom., Paris, Jan. 1819, 3 me ser, 8, 9. 

 Type: H. cornucopice, Defr. Capulus (part), Montfort, 1810. Amal- 

 thea a, Schumacher, 1817; not Atixilfln H*, Montfort, 1810. Pileopsis 

 (pars), Lamarck, 1822. Hipponyx, Blainvillc, 1824. Krehsia, Mb'rch, 

 1877. M alluvium, Melvill, 190(5. 



Animal oval or suborbicular, conical or depressed ; foot very thin, 

 a little thickened towards the margin ; head globose, separated from 

 the body by a, neck-like constriction ; eyes upon swellings of the 

 tentacles. 



Shell thick, obliquely conical, non-spiial, apex somewhat posterior 

 and directed backwards, surface rugose or longitudinally grooved or 

 cancellated ; muscular impression horseshoe-shaped ; base of attach- 

 ment (opercular piece), when present, thick. 



Distribution. Warm seas. 



Fossil. Cretaceous to Pliocene. 



Found fossil in New Zealand : H. mdiatus, Button, in the 

 Miocene. 



1. Hipponix hexagonus, Suter, 1906. Plate 44, fig. 1. 



Amnlthea hexagona, Sut., T.N.Z.T., xxxviii, 19(.)."> (1906), -326. Hipponyx 

 cornucopice, Lamarck : Hutton, C.M.M., 32 ; not of Lamarck. H. aus- 

 tndis, Lam. : Hutton, J. de Conch., 1878, 30 ; M.N.Z.M., 88 ; not of 

 Lamarck. 



Shell solid, conical or depressed, with a posterior apex. Sculpture : 

 Young shells show strong radiate riblets, crossed by very numerous 

 concentric lamelke ; adult shells have almost always a rugose surface, 

 the sculpture of the young shell having been lost through corrosion, 

 sometimes, however, traces of the riblets may be seen near the margin, 

 and concentric ridges can be distinguished. Colour greenish-white ; 

 the interior has a light-green central area, the margin light purple. 

 Aperture more or less distinctly hexagonal, but rarely pentagonal ; 

 margin sharp, uneven, sometimes slightly denticulate ; muscular im- 

 pression distinct, horseshoe-shaped, rather narrowly open in front. 



Diameter, maj., of aperture, 22 mm. (large specimen) ; height vary- 

 ing from about 6mm. to 10 mm. 



Dent ition unknown. 



Tt/ne in my collection. 



!/ L */ 



Hob. Tauranga (type) ; Chatham Islands ; South-west Point, 

 Bluff (Captain Bollons). 



Remarks. Captain Bollons found the shells forming a cluster on 

 a rock, closely in touch with one another, hence the more or less 

 hexagonal outline of the shells. 



Fain. CALYPTR^IID^], Broderip. 



Animal with a distinct head and lengthened muzzle, slit at its 

 extremity ; tentacles subulate, carrying eyes near their external base ; 

 foot short, rounded oval ; the single branchia finely and deeply pecti- 



