9 
Volume 21. Number 2. February, 1919. Whole Number 166. 
A Popular Review and Record for the Pacific Coast. 
The oldest scientific magazine west of the Mississippi. 
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Current or back numbers 25 cents each (as far as available; 
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centric ridges, stronger anteriorly, sparser toward the beaks, and 
obsolete on dorsal area behind; there is an obscure radial depres- 
sion anteriorly, and 2 obscure radial ridges on each side of the 
impressed escutcheon where the dorsal margin of the valves is 
prominently elevated, there are about 12 anterior and 18 poster- 
ior teeth, the resilifer is small, rotund, and subumbonal; there 
is'a small mesial ridge near the end of rostrum internally. Length 
12, height 5, diameter 2.6 mm. North of Santa Barbara Islands. 
21:0058 Leda hamata, Cpr. 1864. 384, 853, 1446. Puget Sound 
to Panama. 
21:0059 Leda hamata limata Dall. Off Santa Rosa Island, Cal. 
In this variety the strong concentric sculpture is subject to 
extraordinary mutations: in one extreme the surface of the disk 
is perfectly smooth; in another there are a few very coarse con- 
centric ridges near the umbones; in still another the umbonal 
ridge is smooth, and the ridges appear near the basal margin 
only. Ranges south to La Paz. 
21:0060 Yoldia oleacina: Dall. Arctic Ocean. 
21:0061 Yoldia secunda Dall. Alaska, Clarence Strait. 
21:0062 Yoldia beringiana Dall. Bering Sea (to Anacapa Is- 
land, Cal.). 
21:0063 YVoldia orcia Dall. Off San Diego, Cal. 
Shell small, thin, pale olive, brilliantly polished, smooth, 
equilateral; base deeply arcuate, beaks not prominent, the poster- 
ior end slightly compressed, pointed and attenuated, the anterior 
end rounded; hinge with 8 anterior and 6 very minute posterior 
teeth, the resilifer subumbonal, extremely small. Length 4.5, 
