The Cambridge natural history . Fig. 190.—A, Tridacna scapha Lam. ; B,Cardimn enode Sowb., showing the inter-locking of the ventral margins. tions or ribbings of tlie surface of the shell, the upper ends ofwhich impinge upon the dorsal margin and mark it in a waywhich is quite recognisable when the shell is thin. Similarcrenulations, residting in interlocking of the valves, are notVOL. Ill T 2 74 IIINGE-TEETH AND OTHER PROCESSES chap. uncommon upon the ventral margin in certain genera (Fig. 190).The mechanical effect of these continued riblets, when fittedtogether on the opposing valves, would
The Cambridge natural history . Fig. 190.—A, Tridacna scapha Lam. ; B,Cardimn enode Sowb., showing the inter-locking of the ventral margins. tions or ribbings of tlie surface of the shell, the upper ends ofwhich impinge upon the dorsal margin and mark it in a waywhich is quite recognisable when the shell is thin. Similarcrenulations, residting in interlocking of the valves, are notVOL. Ill T 2 74 IIINGE-TEETH AND OTHER PROCESSES chap. uncommon upon the ventral margin in certain genera (Fig. 190).The mechanical effect of these continued riblets, when fittedtogether on the opposing valves, would be to prevent tlie valvessliding upon one another while closing, or after being there would be a probability of their surviving, even aftertlie ribbing had disappeared from the surface of the shell, tlieincreased strength given by the hinge compensating for, andmaking it possible to do without, the extra strength supplied bythe ribs. It is therefore possible that the teeth of the Nuculidaeand Arcadae, which have
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
