. The edible clams, mussels and scallops of California. Fig. 6. Modiolus rectus. One-half natural size. bb. Adductor muscles equal or nearly so; umbo not at end of valve in forms here • treated (except Solen) ; mantle edges fused in at least two places forming two siphonal apertures, which are usually prolonged into siphonal tubes; adults without byssal attachment; usually capable of moving about by means of the foot; all capable of burrowing to some extent and habitually doing so ; color of shells various; never black. True clams c. Valves closing completely, or at least with no marked gaping
. The edible clams, mussels and scallops of California. Fig. 6. Modiolus rectus. One-half natural size. bb. Adductor muscles equal or nearly so; umbo not at end of valve in forms here • treated (except Solen) ; mantle edges fused in at least two places forming two siphonal apertures, which are usually prolonged into siphonal tubes; adults without byssal attachment; usually capable of moving about by means of the foot; all capable of burrowing to some extent and habitually doing so ; color of shells various; never black. True clams c. Valves closing completely, or at least with no marked gaping, siphons com- pletely retractile and not visible in the closed shell, d. Shells thick and strong, animal symmetrical with similar valves, siphons usually united and short; if burrowing not lying on one side, e. Siphons extremely short, not projecting beyond shell when extended; no pallial sinus; not burrowing deeply. (See Fig. 7; compare with Fig. 8). Cockles Cardium. Fig. 7. Cardium cor- dis. One - half natural size. Fig. 8. Donax laevigata. One and one-half times natural size. f. Radiating ribs conspicuous and sharply raised above surface, g. Ribs roughened. C. cordis p. 28; pi. 5 , fig. 2 gg. Ribs with rows of spines. C. quadrigenarium p. 28; pi. 5 , fig. 1 ff. Ribs faint and gently rounded. C. elatum P. 29. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Weymouth, Frank W. [from old catalog]. Sacramento
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishersacra, bookyear1920
