116 HALIOTIS. 



Group of H. ncevosa. 



These shells are flat, rounded, the spire more than usually central. 

 They form a transition to the section Padollus. 



H. cunninghami Gray. PL 7, fig. 38. 



Shell very large, rounded-oval, flattened and disc-shaped ; dis- 

 tance of apex from margin something more than one-fourth the length 

 of shell. 



The outline is more orbicular than in If. ncevosa, and flatter. 

 The right side is less curved than the left. The perforations stand 

 upon a carina. It is a solid shell. The specimen before me is dull 

 red, with obliquely radiating revolving flames of whitish-yellow on 

 the earlier part of the body -whorl. (Reeve describes it as " reddish- 

 brown, variegated with green and darker brown." Philippi says 

 the coloration is a marbling of large spots of pale green, whitish, 

 brownish-red and dark reddish-brown, the brownish-red predominat- 

 ing.) On the earlier portion the surface is finely spirally striated, but 

 this sculpture becomes obsolete upon the greater portion of the body- 

 whorl, giving place to coarse wrinkles of growth. There are also low 

 radiating waves or folds in places. The spire is not much elevated. 

 Inside it is light, very iridescent, red and silvery predominating. 

 Columellar ledge or plate flat, broad, obliquely truncated below, of 

 about equal width all around. Cavity of spire large, very broad, 

 shallow. Number of open perforations very variable; usually 7 in 

 young shells, about 5 or 6 in adults, very old individuals having 4. 



Length 190, width 155, convexity 35 mill. 



Australia. 



H. cunninghami Gray, in appendix to King's Voyage ii, p. 494. 

 — Reeve, Conch. Icon., f. 3. — Sowerby Thes. Conch, v, p. 30, f. 

 36. — Weinkauff, Conchyl. Cab., p. 25, 1. 10, 11. — H. ncevosa Desh. 

 in Lam., An. s. Vert, ix, p. 34, excl. syu. — Philippi, Abbild. u. 

 Beschreib. i, t. 2, 3 (not ncevosa Martyn). — H. gigantea Mke., Spec. 

 Moll. Nov. HolL, p. 31 (not of Chemnitz). 



A magnificent species, very large and flat, the apex more central 

 than in the allied H. ncevosa, and the cavity of the spire consequently 

 wider. The disc is covered with fine spiral strise, but in old in- 

 dividuals these become obscure. 



H. ncevosa Martyn. PL 11, figs. 56, 60 ; pi. 5, fig. 26. 



Shell large, rounded-oval, much depressed, the distance of apex 

 from margin one-fifth the length of shell ; sculptured with fine spiral 



