. The edible clams, mussels and scallops of California . 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, sip
. The edible clams, mussels and scallops of California . 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
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Photo credit: © The Bookworm Collection / Alamy / Afripics
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishersacra, bookyear1920
