CLASS PELECYPODA 
117 
Genus MILNERIA Dali, 1881. 
Shell with two left and three right cardinals, the posterior left lateral, 
posterior and anterior right cardinals minute and hardly recognizable 
except in very well-developed specimens, in which the formula is 
r^n ‘ ^he female has a dome-like indentation arising from the 
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ventral margin of the valves, which is closed only by an extension of the 
mantle edge and therefore not included within the shut valves. The 
animal is minute, byssiferous, and a nestler on flat surfaces, like the backs 
of the shells of Haliotis. (Dali.) 
Type. Ceropsis minuta Dali. 
Distribution. California. 
Milneria minima Dali, 1871. 
Plate 54, figs. 29 to 31. 
Amer. Jour. Conch., 7 :152; pi. 16, figs. 5, 6. 
Shell minute, trapeziform, white, with a thin brownish epidermis. 
Umbos prominent, nearly terminal. Anterior margin rather strongly 
angulated; basal margin straight, or a little concave; lower posterior 
extremity angulated; upper posterior angle rounded off; posterior margin 
rather oblique. Hinge line smooth, rather broad. Ligament conspicuous, 
moderately long. A rounded carina passes from the umbo to the lower 
posterior angle, above which are from two to five radiating ribs. General 
sculpture of sharp elevated lines of growth, which become vaulted scales 
on the ribs. Margin lightly crenulated. Interior polished; muscular and 
pallial impressions indistinct. Long., .14; lat., .08; alt., .075 inch. (Dali.) 
Type in U. S. N. M. Type locality, Monterey, California. 
Range. Monterey, California, to Rosario Bay, Lower California. 
Milneria kelseyi Dali, 1916. 
Plate 54, figs. 19 to 23. 
Proc. U. S. N. M., 52:408; 8: pi. 25, figs. 4, 7. 
This species has been confused from the beginning with M. minima 
Dali and is best diagnosed comparatively. The latter has the radial 
sculpture, especially the four strong ribs of the posterior part, coarsely 
and conspicuously imbricated, with no very marked keel from the umbo 
to the posterior basal angle. The shell in a general way is in all respects 
less angular. M. kelseyi has a conspicuous ridge extending from the umbo 
to the posterior basal angle; the imbricated ribs are less conspicuous, the 
scales smaller and less prominent, the anterior end more attenuated, the 
shell wider and more depressed, and is apparently larger when mature. 
Length, 11; height, 3; diameter, 4.5 mm. (Dali.) 
