MOLLUSCA. — HEDLBY. 
43 
Nacella illuminata * has been reported from Macquarie Island but does not 
occur in this collection. Our shells differ from Gould’s figure of that Auckland Island 
species by being narrower with finer and more numerous ribs, lower and less excentric 
apex, and different colour pattern. 
Patella depsta Reeve, from St. Paul, as figured by Velain,t and which also appears 
to be a Nacella , differs by still finer radial sculpture. 
In alcohol, the animal (pi. vi., fig. 68) is buff. On the mantle margin is an 
uninterrupted linear series of simple papilla', every fourth (but sometimes every second) 
one of which is black, larger, and much contracted. These are more developed than in 
other genera of limpets. For comparison, a drawing of the animal (fig. 69) of Cellana 
variegata Blainville, from life, is here submitted. Within the papillae are set the branchial 
lamellae, continuous but diminished in front. For comparison, a sketch is here added 
of Patella squamifera Reeve (text fig. 2), a Sydney specimen, from life, to show the 
continuous row as expressed in another genus which has no pedal fringe. 
The foot of the Nacella is large and muscular with a double margin in front. Half 
way up the stem is a broad undulating fringe above which the skin is more smooth and 
tender, thus suggesting that the flounce round the foot meets the mantle edge to form 
a branchial chamber. If the pedal fringe of Nacella be the homologue of the epipodial 
skirt of the Trochidse, then this genus may be nearer than other limpets to the primitive 
Diotocardian stock. Davis and Fleure remarked that, as a rudimentary and transient 
feature, this fringe occurs in the young of Patella vulgata.% 
If I have correctly identified this species it has only been described from immature 
specimens. The adult may be characterised as follows :—Shell large, solid and elevated ; 
of variable shape, the apex being usually one-fourth of the total length from the anterior 
end, but varying from one-third to one-sixth, height usually less than one-half the 
breadth. Colour, externally chestnut variegated with tawny olive ; interior nacreous, 
* Suter.—Subantarct. Islands of N. Zeal., i., 1909, p. 6. 
f Velain.—Arch. Zool. Exper., vi., 1878, pi. iv., figs. 13-18. J Davis and Fleure.—L.M.B.C. Memoirs, x., 1903, p. 15 
