surface the limpet has no room for lateral expansion, the 
creature, on increasing its growth, naturally takes the line 
of least resistance, and grows in height. This is specially 
noticeable in the H. ornatus, some specimens of which are 
very broad and flat, while others again have a relatively 
small base and a high sharply-pointed apex like a dunce’s 
cap. So you see, one has to be careful to note the charac- 
teristics of a limpet shell, such as age, colour, size, shape 
and sculpture, before venturing to determine the species. 
The silvery variety of the H. radians is found through- 
out New Zealand. Mount Maunganui; Lyttelton. 
HELCIONISCUS RADIANS var. FLAVUS (helcion, 
a breast collar; radians, having rays; flavus, yellow ).— 
This is the yellow variety of the species, the interior being 
cream colour or bright orange, yellowish white and old 
gold, varying very much according to age. Young speci- 
mens are more brightly coloured, while the older shells 
show a paler tint, the formation of pigment being, as in 
all animal life, a vital” process declining with age. This 
subspecies is found at Napier, living on the “red sand- 
stone cliffs, into which it makes hollows, so that it is diffi- 
cult to detach them without cutting the rock away.” (Ire- 
dale). “Small shells are, as a rule, depressed, but adult 
specimens have mostly a high conical form.” (Suter). 
Both of which statements go to prove that the alteration 
of shape is due to the nature of the bed. 
Found at Napier; Gisborne; East Cape; Kaikoura; 
Stoneyhurst ; Chatham Islands. 
HELCIONISCUS RADIANS var. OLIVACEUS— 
(helcion, a breast collar; radians, having rays; olivaceus, 
olive coloured ).—This variety is described as having about 
seventy ribs, fine and uniform in size, but the external vari- 
ation is not always characteristic enough to enable one to 
identify the shell without examining the interior. Some 
have thick and large ribs with finer ribs between them, 
while others have only fine ribs, smaller or larger as in the 
species; but it should be noted that the thicker and heavier 
shells are those which have the larger ribs, pointing to a 
reinforcement of the strength of the structure, often ob- 
served where limpets are attached to rocks exposed to the 
full force of heavy breakers. Internally the olivaceous sub- 
species is olive green in the central area, with a broad white 
porcellanous band, and a very narrow black edging at the 
extreme margin. It is rather a rare shell. 
Found at Sumner and along the East Coast of the 
South Island to Preservation Inlet. 
17 
Plate IT 
No. 5-5a. 
Plate IT 
No.3 
Sea Shells 
of New Zealand 
