46 Marine Shells of the Western Coast of Florida 



roughly trigonal in shape with apex at umbos; widest at junction 

 of lateral and ventral margins. Ground color white with fine pencil- 

 lings of reddish brown. Slightly inequivalve with small, flat area of 

 attachment near umbo of right valve. Each valve has an equal num- 

 ber of strong radiate plications sometimes slightly serrate, lateral 

 margins minutely serrate. Hinge typical of family; interior of valves 

 white, plicate towards margin; single, subcentral, laterally placed 

 musclar impression, often a little elevated; simple pallial line. 



Dredged in two to six fathoms. 



Gastrochaena burrows into the valves of living Plicatida, and 

 small shells of Rupellaria typica have been found in its cavities. In 

 one instance an individual of each species was in one burrow. Perry 

 has found living Gastrochaena in burrows which had no communi- 

 cation with the outer surface of the valve. 



Family PECTINIDAE 



All seas have representatives of the Pectinidae, and their bathy- 

 metric range is from shallow water to profound depths. Shells of 

 many species are brightly colored in shades of red, yellow, rose, 

 pink and purple. The mollusks are sensitive and active and able to 

 change not only position but also location by a rapid opening and 

 closing of the shell valves. At rest they lie upon the right valve which 

 is often colorless or paler than the left valve, and when the moUusk 

 is undisturbed the valves of the shell remain slightly separated, 

 showing the closely plaited mantle edge studded with brilliant metal- 

 lic-blue eyes placed at intervals corresponding to the scallops in the 

 shell's margin. 



Aristotle and Pliny were acquainted with several species of this 

 group and made the comparison of the ribbed shells to the teeth of 

 a comb. It is quoted from Pliny that little fleets of scallops may be 

 seen floating upon the surface of the sea, with one valve raised to 

 make a sail, but this phenomenon has not been noted since Pliny's 

 time. 



The life time of Pectens is thought to be about two years. Re- 

 productive maturity is reached within a year. 





