NEW ZEALAND SHELLS. _ 353 
essential to success in eradicating fungus. Next, rock salt should 
be used in wells below the sluices of the reservoir, to yield its 
well-known health-giving properties to the water as it passes 
over it. All rivers, caulds, and dams, should be furnished with 
the most approved fish-ladders, so as to afford a clear run to the 
salmon in low states of the rivers, and stake nets, with other 
nets, must be removed one mile from the mouths of the rivers. 
If these, or like remedies, be not adopted, I see no other way of 
assisting nature to cure the salmon of British rivers of this fatal 
disease. 
Roslyn, December, 1882. 
NEW ZEMAN D) SHELLS OF sTHE “CHALLENGER ‘ 
EXPEDITION. 
BY THE REV. R. BOOG WATSON, F.L.S., ETC. 
(Continued from Page 321.) 
<_ 
PLEUROTOMA (SURCULA) ISCHNA, Watson, Proc. Linn. Soc., 
LOO. XV, 0: A032. 
meeeo. july 10,1874. Lat 37°. 34° S; lon.*179.. 22’ E., N.E. 
from New Zealand. 700 fms., grey ooze. Bottom temperature, 
40°. 
Shell.—Higch, narrow, conical, blunt, with a contracted base 
and longish snout, little sculpture, yellowish grey, porcellaneous. 
Sculptuve.—Longitudinals—these are only strongish regular lines 
of growth, which rise into small tubercles, especially on the upper 
whorls ; between the stronger lines the surface of the shell is 
delicately fretted with other very minute sharp lines. S#zrals.— 
The whorls are faintly keeled above the middle by a spiral thread, 
which is a little stronger and more prominent than any of the 
others. Close above the suture is another, almost as strong, and 
which also slightly carinates the whorls ; half-way between these 
is a finer thread, which tends to split into two very fine threads ; 
at the suture, but visible beyond the mouth, is another thread, 
which here defines the base. The longitudinals rise into very 
small tubercles as they cross the spirals ; but this feature is much 
the strongest on the upper whorls, which are reticulated ; on the 
last whorl it is feeble. Between the keel and the suture lie three 
very fine, equally-parted threads. On the base and snout are 
about twelve pretty equal fine threads. Colouy a faintly 
yellowish-gray. pidermis extremely thin, smooth. Spire conical, 
with an almost unbroken profile, the whole being scarcely convex. 
A pex.—There are barely two embryonic whorls, smooth, globose, 
not flattened down at the tip, which, however, is slightly im- 
mersed. Whorls, 7 in all, feebly keeled with a just perceptibly 
concave line from the suture to the keel, and from the keel to 
the suture below. Just above the suture there is a slight con- 
