Nacella.] GASTROPODA. 77 



less stained and blotched with chestnut-brown, apex bronze. Apex 

 inclined anteriorly, situate at about the anterior fifth, anterior slope 

 straight to concave. Interior iridescent bronze, radiately grooved, 

 grooves sometimes partially obsolete. 



Length, 33 mm. ; breadth, 24 mm. ; height, 9 mm. : Length, 

 31 mm. ; breadth, 23 mm. ; height, 13 mm. (specimens from Mac- 

 quarie Island). 



Dentition. Teeth of the lingual ribbon slightly hooked, in pairs, 

 scarcely diverging ; the central pair 2-pronged. the inner prong much 

 larger, spear-head shaped ; the lateral pairs alternating with the 

 central ones are 4-pronged, the innermost prong smallest, the next 

 2 subequal, and the outside one situated nearly at right angles to the 

 rest of the tooth, about the same size or a trifle larger. (E. A. Smith.) 



Type in the British Museum. 



Hob. Campbell Island (Filhol) ; Macquarie Island (A. Hamilton). 

 Tierra del Fuego, Falkland Islands, Kerguelen Island ; everywhere 

 common on the submerged fronds of floating kelp (Macrocystis). 



Remarks. The radiate ribs are very variable in size and number ; 

 in one specimen I have they coalesce to broad ribs, having now and 

 again a fine riblet between them. The crowded, strongly raised, and 

 undulating concentric ridges are characteristic of the species. Most 

 of the shells are covered with Nulliporites. 



2. Nacella illuminata, Gould, 1846. Plate 7, fig. 8. 



Patella illuminata, Gould, P. Bost. S.N.H., ii, 1846, 149. Nacdla illu- 

 minata, Gould, U.S. Expl. Ex., 340, atlas f. 441. Patinella illuminata, 

 Gould: Hutton, P.L.S. N.S.W., ix, 376. Helcioniscus illuminata, Gould : 

 Pilsbry, Mean. Conch. (1), xiii, 142, pi. 70, f. 40-42. Nacella illuminata, 

 Gould : Suter, P. Mai. S., vi, 353 ; Subantarct. Islds. N.Zeal., i, 6. 

 Patella terroris, Filhol, Compt. Rend., xci, 1880 ; Miss. I.C., 529. 



Shell elevated conical, ovate, arched. Surface covered with 

 numerous small obtuse radiating riblets, numbering 20 to 25, with 

 from 1 to 3 intervening striae ; concentric lines of growth crowded, 

 very faint. Colour sooty, with scattered yellowish spots, about 20 in 

 number, somewhat regularly disposed, which are transparent when 

 held up to the light, those near the margin elongated. Apex at about 

 the anterior fourth or third, sharp, directed forward. Interior a very 

 dark claret colour, with brilliant silky and golden reflections, and 

 yellow spots, corresponding to those of the exterior ; central area 

 dull buff colour. 



Length, 38 mm. ; breadth, 32 ; height, 16 mm. 



Dentition. Hutton, T.N.Z.I., xv, 128, pi. 16, f. C. Plate 1, fig. 2, 

 is a copy. 



Animal. The foot has on its sides a scalloped frill, interrupted in 

 front ; the branchial cordon is complete, not interrupted in front. 



