Perkins.] 142 [November 3, 



SAXICAVID^E. 



Saxicava Fleur de Bell., 1802. 



Saxicava arctica Linn., Syst. Nat. Saxicava pholadis Lam., 

 An. sans Vert, Vol. v, p. 501. Saxicava distorta Say, Am. Conch., 

 p. 10G, 1822; Gould, Invert. Mass., p. 61, fig. 40; De Kay, Moll. 

 N. Y., p. 227, pi. xxxiii, fig. 309. 



Not common. Lives in sand near low water. Animal white; 

 mantle closed, except a small pedal opening; gills long and narrow, 

 brown; foot when contracted flattened, conical, with a deep byssal 

 groove, blunt at the end; byssus composed of horn-colored fibres; 

 palpi broad at the base, straight posteriorly, curving irregularly to a 

 point in front; siphons distinct only at the tips, which are thickly 

 covered with papillae. 



MYID.3J. 

 Mya Linne, 1747. 



Mya arenaria Linn., Syst. Nat., 12thed., p. 1112; Lam., An. 

 sans Vert, Vol. vi, p. 74; Gould, Invert. Mass., p. 40; De Kay, 

 Moll. N. Y., p. 240. Mya mercenaria et acuta Say, Am. Conch., p. 

 103, 1822. 



Occurs wherever there is mud or sand between high and low 

 water in great abundance, and in the spring the shore is covered 

 for long distances with young shells about an inch long. Animal 

 yellow, mantle closed; gills broad and thin, nearly equal, rounded 

 before, pointed behind; foot when contracted sub-spatulate, obtusely 

 pointed; palpi long and narrow, outside smooth, inside striated; 

 siphons united except at the very end ; tube long, near the end sur- 

 rounded by a row of papillae ; around the ventral opening are two 

 rows of unequal papillas; the dorsal opening is also fringed with 

 smaller ones ; each has around the inside a black line. 



MEASUREMENTS. 



Igt1 



i of shell 73 mill. 



Breadth 47 mill. 



Height 34 mill. 



u 



gills 21 " 



" 30 " 





(( 



foot 11 " 



" 10 u 





a 



palpi 22 " 



" 5 " 





