ILLUSTRATIONS AND DESCRIPTIONS OF NEW, UNFIG- 
URED, OR IMPERFECTLY KNOWN SHELLS, CHIEFLY 
AMERICAN, IN THE U. S. NATIONAL MUSEUM. 
By William He ale y Dall, 
Honorary Curator, Division of Mollusks. 
During the last thirty years a larg-e number of species have been 
described by me in various publications which it was, at the time 
of publication, impracticable to figure. There are also a number of 
species described b}^ others which have either been inadequately illus- 
trated, figured in almost inaccessible publications, or not figured at 
all. Of the many undescribed species in the national collection some 
few have been distributed with manuscript names, for reasons which 
seemed sufficient at the time. With the view of suitably illustrating 
these species and eventually preparing an illustrated list or manual 
for American collectors and students, I have been accumulating a store 
of drawings of which the present paper includes a selection. Manj' 
more, especially species obtained by Mr. and Mrs. Oldroyd in the 
vicinity of San Pedro, California, are reserved for a future occasion. 
With the exception of the first species, a remarkable Malayan 
JVanina, the forms figured are all American, and for convenience are 
divided into three series, including, respectively, the species of land 
shells, the East American marine forms, and the marine species from 
the Pacific coast. 
Some systematic and nomenclatorial notes on the species and genera 
illustrated, and especially on the Bucc mince and Ohrysodojninm so 
richly developed on our northwest coast, are included, together with 
some descriptions of new forms and a review of the northern species of 
the genus Boreotrojj/ion, and it is hoped as a whole that the paper will 
furnish welcome information to many students of American mollusks. 
LANDSHELLS. 
NANINA (MACROCHLAMYS?) DIADEMA Dall. 
Plate XXVII, figs. 1, 2, 3. 
Nanina {Maerochlamysf) diadema Dall, Nautilus, XI, No. 4, Aug., 1897, p. 37. 
Collected in the vicinity of Prang, Malay Peninsula, by Dr. W. L. 
Abbott. U.S.N.M., 150277. The color is an olivaceous 3^ellow-brown. 
Proceedings U. S. National Museum, Vol. XXIV— No. 1264. 
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