238 PROCEEDINGS OF SECTION D. 
to them. An inoffensive kind, Zimnoria segnis, has been de- 
scribed by Chilton (a) from Lyttelton, New Zealand, as living, 
not on wood, but on the roots of the giant kelp Macrocystis. 
The Zimnoria can endure considerable cold, and consequently 
attains higher latitudes than the other boring Crustaceans. It 
is about the size of a gram of rice, is a common and gregarious 
species, and commits much destruction. Wood is riddled by it 
in numerous small perforations, perpendicular to the surface, 
until reduced to the semblance of a sieve, or a target struck 
by shot. 
White writes :—“ They ply their masticatory organs with such 
assiduity as to have reduced great part of the woodwork which 
constitutes their food into a state resembling honeycomb. One 
specimen was a portion of a 3-in. fir-plank, nailed to the north 
pier-about three years before, which is crumbled away to less than 
an inch in thickness ; in fact, deducting the space occupied by the 
cells which cover both surfaces as closely as possible, barely half 
an inch of solid wood is left, and though its progress is slower in 
oak, that wood is equally liable to be attacked by it (6). 
It was by depredations at the Bell Rock Lighthouse, where it 
was first observed by the celebrated engineer, ‘Robert Stevenson, 
that it first came into notice as a member of the British fauna. 
White thus refers to the circumstance :—“ It occurs in the 
ereatest abundance at the Bell Rock, in the old woodwork used 
whilst the lighthouse was building, which it perforated in a 
most alarming manner, entering to the depth of 2 in. or more, 
boring in every direction. They seldom or never deviate from a 
straight line in their perforations, unless interrupted in their 
progress by a knot in the wood, when they pass round it.” A 
full account of Z. dignorum is given by Bate and Westwood (ce). 
The Chelura terebrans is rarer than the foregoing, but is 
larger and more destructive creature. Allman (d) has given an 
excellent account of its structure and economy. He found the 
alimentary canal full of wood in process of digestion, which 
proves that the animal excavates the timber to procure food 
rather than shelter. Timber carved by it differs in appearance 
from the work of the Zimnoria. In the latter we find narrow, 
cylindrical burrows running deep into the interior, while the 
excavations of Chelwra are considerably larger and more oblique 
in their direction, so that the surface of the timber thus under- 
mined by these destructive animals seems to be ploughed up 
rather than burrowed into (e). 
(a) Chilton. Trans. New Zealand Inst., xv., 1882, p. 76, Pl. ii., Fig. 2 
(6) White. Popular History of British Crustaceans, 1857, p. 229, 
oh (c) Bate and Westwood. History British Sessile-eyed Crustacea, li., 1868, pp. 351-6, 
igs. 
(d) Allman. Ann. Mag. Nat. Hist. (I.), xix., 1847. pp. 361-370, Pls. xiii., xiv. 
(2) Snow. Proc. Am. Soc. Civil Engineers, xxiv., 1898, Pls. xxviii. and Xxx, 
