Transactions and proceedings of the New Zealand Institute . and rugose at its posterior portion. Inthe left valve there is a rather long compressed lower anteriorrugose pseudocardinal, the upper tooth is quite rudimentary;the upper lateral tooth is a little higher and more rugose pos-teriorly than the other. Interior bluish-white, pearly, a littleblotched with olive in the umbonal cavity, where there arerather large and deep dorsal scars. The adductor-muscle scarsare shallow. The young specimens are slightly winged. This subspecies is nearest to the typical aucklandica, but isdistinguished fro
Transactions and proceedings of the New Zealand Institute . and rugose at its posterior portion. Inthe left valve there is a rather long compressed lower anteriorrugose pseudocardinal, the upper tooth is quite rudimentary;the upper lateral tooth is a little higher and more rugose pos-teriorly than the other. Interior bluish-white, pearly, a littleblotched with olive in the umbonal cavity, where there arerather large and deep dorsal scars. The adductor-muscle scarsare shallow. The young specimens are slightly winged. This subspecies is nearest to the typical aucklandica, but isdistinguished from it by its exceptionally compressed form, thethinness of the shell, the strongly marked and close concentriclines, the more tapering posterior margin, and the feebly developedpseudocardinals. The radiate nodulous sculpture is found inmany specimens of menziesi and its subspecies. Adult specimen—Length, 45 mm. ; height, 24 mm. ; diam., 8 in my collection. I have much pleasure in naming the subspecies in honour ofits discoverer, Mr. Keith 240 Transactions.—Zoology. Diplodon lessoni, Kiister (1856). Unio lessoni, Kiister, Conch. Cat., 1856, p. 135, pi. xxxvi., fig. from New South Wales. Lake Wakatipu (Stat. 37—Dredged in 10 ft. to 30 ft.).— Nine specimens wereobtained. Shell (fig. 4)oblong, obliquely trun-cated behind, com-pressed, inequilateral,beaks strongly erodedin all specimens, notrace of sculpture left ;surface with distantflatly elevated rest-marks, which, togethers * with the intervening space, are covered withvery fine thread-like concentric fines ; towards the base and pos-terior margin the growth-lines are more distinct and slightlyfoliated. There is no trace of radial sculpture. The epidermisis olive to dark-brown, dull. Interior bluish nacre, with yel-lowish patches under the beaks, where there are several deepsmall dorsal scars. Right valve : The pseudocardinals are com-pressed, the anterior upper tooth is small, grooved, the posterio
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