The Development of Kerguelenella stewartiana (Powell) 
( Gastropoda : Siphonariidae ) 1 
G. A. Knox 2 
A species OF siphonarid, Kerguelenella stew- 
artiana , was described from Stewart Island by 
Powell in 1939- During December, 1950— 
January, 1951, I spent several weeks investi- 
gating the intertidal ecology of the rocky 
shores of Stewart Island in the vicinity of 
Half Moon Bay. Kerguelenella was found in 
two localities, Akers Point and Ringa Ringa. 
Powell records the species from Akers Point 
(the type locality) as, "common on seaweed- 
covered rocks towards high water” and from 
Mason Bay on the west coast of the Island, 
from, "low water under stones.” 
A striking feature of the distribution of 
Kerguelenella was that it was found only in the 
form of isolated colonies with a restricted 
horizontal range. Intensive search over about 
ten miles of coastline from Horseshoe Bay 
to the upper end of Paterson Inlet failed to 
reveal any further colonies. The vertical dis- 
tribution of the species is also interesting. 
Both colonies were on more or less exposed 
rocks facing southeast. The Akers Point col- 
ony was found on the vertical seaward faces 
of large broken rocks, and the Ringa Ringa 
colony on the seaward side of a large isolated 
rock mass rising from a broken platform at 
about mid-tide level. All the specimens found 
lay in a zone extending 4 feet upward from 
1 The collection of the material for this study was 
made possible by a travelling grant from the Research 
Committee of the University of New Zealand. Manu- 
script received April 14, 1954. 
2 Department of Zoology, Canterbury University 
College, Christchurch, New Zealand. 
the upper foot of the zone occupied by the 
red seaweed, Bostrychia arbuscula . This species 
is a conspicuous feature of the intertidal zona- 
tion of the Stewart Island region, forming a 
well marked band up to 3 feet in vertical 
extent, the upper limit lying in the vicinity 
of extreme high water spring tides. The ver- 
tical distribution of Kerguelenella thus lies 
above mean high water spring tides and no 
specimens were found below this level. 
Hubendick (1946) records Kerguelenella stew- 
artiana from Port Ross, Auckland Islands, 
"under stones at low tide level.” Powell 
(1939), however, regarded the Stewart Island 
species as endemic. Judging from the ob- 
served habitat of Kerguelenella at Stewart Is- 
land the record of the species from "under 
stones at low water” is erroneous. R. K. Dell 
in correspondence states that he has never 
seen a specimen of Kerguelenella under stones 
at the Bounty Islands, Antipodes Islands, or 
Stewart Island, and that they are always found 
on rock faces near high tide. 
On January 16 several small ovoid egg 
masses were found near the upper limit of the 
Bostrychia arbuscula zone of the Ringa Ringa 
colony of Kerguelenella. They were fastened 
singly or in groups of two to four to the 
sides of small crevices. Several were removed 
and subsequent examination under a dissec- 
ting microscope showed that some contained 
a number of limpet-like larvae in an advanced 
stage of development, with brown shells re- 
sembling small specimens of Kerguelenella 
85 
