. The edible clams, mussels and scallops of California. — 16 — ff. Lower edge of pallial sinus not united with pallia! line; cartilage pits unequal, that on the left \alve on a conspicuous projecting tooth; retracted siphons usually not projecting beyond the shell, tip with- out plates; umbo not nearer the anterior end of the shell, g. Umbo central; valves rounded and slightly gaping at the posterior (siphonate) end. Soft-shell Mya arenaria p. 56 ; pi. 17 , figs. 2, 3 gg. Umbo nearer the posterior end of shell; valves truncated and widely gaping at posterior end. Platyodon Platyodon cancellatu
. The edible clams, mussels and scallops of California. — 16 — ff. Lower edge of pallial sinus not united with pallia! line; cartilage pits unequal, that on the left \alve on a conspicuous projecting tooth; retracted siphons usually not projecting beyond the shell, tip with- out plates; umbo not nearer the anterior end of the shell, g. Umbo central; valves rounded and slightly gaping at the posterior (siphonate) end. Soft-shell Mya arenaria p. 56 ; pi. 17 , figs. 2, 3 gg. Umbo nearer the posterior end of shell; valves truncated and widely gaping at posterior end. Platyodon Platyodon cancellatus p. 62 ; pi. 17 , fig. 1. Pig. 17. Mya arenaria. One-half natural size. (A) Interior right valve. (B) Exterior of portion of left valve. dd. Shell with anterior half sharply marked off from posterior, roughened and obviously adapted for boring in rock or clay; hinge region protected either by a membrane or by accessory plates. (See Fig. 14.) e. Shell gaping widely at both ends throughout life; a membrane but no accessory plates covering hinge region. Piddock Zirfaea gabbi p. 63 ; pi. IS , fig. 1 ee. Shell of adult closing completely or gaping only moderately, siphons com- pletely retractile, accessory plates present over hinge region, f. Siphonal end of valve formed in large part by soft epidermal scales ; accessory plates long and slender. Borer Parapholas californica p. 64 ; pi. 19, fig. 1 ff. Siphonal end of valve with epidermal scales which cover the firm shell; accessory plate short and triangular. Rock clam Pholadiclea penita p. 64 ; pi. 19 , fig. 2. 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
