4 The N.Z. Journal of Science and Technology. [Jan. 
the Engineer of the Auckland Harbour Board in July, 1913. There is 
little doubt that it is now to be found in harbours throughout the world, 
though perhaps the destruction caused by it is not so noticeable in these 
days of iron ships and ferro-concrete wharves as it was before these sub¬ 
stitutes for Wood were largely used. 
Limnoria lignorum is a small Isopod, only about 5 mm. in length (see 
fig. 1). It has very short antennae, and short legs which are abundantly 
supplied with hairs and dentate setae, probably used for the purpose of 
removing the portions of timber from the 
bores made by the animal, the boring being 
done by its sharp mandibles. Six species of 
Limnoria have been described, though it is 
perhaps doubtful if they are all really dis¬ 
tinct. All of these appear to be borers, with 
the exception of L. segnis Chilton from New 
Zealand, which lives on the roots of the large 
kelp, Macrocystis, and other seaweeds at or 
slightly below low-water mark. The original 
specimens of L. antarctica Pfeffer, a closely 
allied species from Antarctic regions, was 
found in holes bored in seaweed. I have 
other specimens from Macquarie Island, “ at 
roots of kelp,’’ that appear to belong to this 
species. 
L. segnis is very sluggish in its movements, 
either remaining quite still or creeping about 
slowly on the seaweed when it is removed from 
the water. The numerous hairs on its surface 
are often clogged with particles of mud and 
other extraneous matter. Its existence in 
New Zealand has to be borne in mind when 
dealing with the gribble, because the two are 
almost identical in external aspect, and can be 
distinguished only by some minute characters 
connected with the mouth-parts. 
The two chief points of difference are found 
in the mandibles and in the maxillipedes. In 
both species the mandibles have a sharp 
cutting-edge, which seems to be the chief agent 
used in boring, but in L. lignorum the palp is of fairly large size and 
has the usual three joints,as shown in fig. 2; in L. segnis the palp is 
much smaller, and composed of two joints only (see fig. 3). In these 
two figures the general shape of the mandible itself seems to be some¬ 
what different, but this is mainly due to their having been drawn from 
slightly different aspects ; the tuft of setae shown near the cutting-edge 
of L. lignorum in fig. 2 is also present in L. segnis , but is concealed in 
the view shown in fig. 3. Similarly, the maxillipedes are, on the whole, 
very similar in the two species, but there is a difference in the epipod, or 
portion of the appendage farthest from the median line— i.e., to the right 
in the figures. In L. lignorum (fig. 4) this is triangular in shape and con¬ 
siderably less than half the total length of the maxilliped ; in L. segnis 
(fig. 5) the epipod is club-shaped, widening towards the distal end, which 
is rounded, and is fully two-thirds as long as the maxilliped. 
Fig. 1 .—Limnoria lignorum 
Rathke; female (after 
Sars). 
