Chamidae 61 



Subgenus FTEROMERIS^e conrad, 1862 

 Veiiericardia perplaiia" (Conrad) PI. 10, fig. 58 



Alt., 7; length, 6; diam., 2 mm. Shell small, obliquely trigonal; 

 bluish gray with zigzag markings of brown; equivalve; inequilateral; 

 12 to 14 smooth radiate ribs which increase in width toward margin; 

 umbos sharp; two cardinal teeth in left valve, one in right valve; 

 interior purple-brown; two muscular impressions and simple pallial 

 line; margins dentate within. 



Dredged in one to seven fathoms. 



Family CHAMIDAE 



Members of the family Chamidae are native to warm and trop- 

 ical seas. All have fixed, heavy, inequivalve shells with spiral umbos 

 and an external ligament. Fixation by either the right or left valve 

 is a generic character; the fixed valve is always deeper. Shells of 

 Chamidae are frequently attacked by the burrowing sponge Cliona 

 and are often mined by boring mollusks. 



Genus CHA^IA Linne, 1758 

 rhama's congregata Conrad PI. 10, fig. 59 



Alt., 25; length, 27 mm. Shell fairly thick, orbicular, attached 

 by left valve which is larger and deeper than the upper valve and 

 with its umbo well above ligamentary area. Umbos turn to right when 

 shell is observed in its attached position. Area of attachment variable. 

 On a flat surface it is apt to include almost entire lower valve. 

 Sculpture of elevated, radiating ridges and more or less foliate lamel- 

 lae along concentric growth lines; usually red, with colors deepest on 

 ridges and foliations; there is also a pure yellow form. An external 

 ligament which follows curve of the umbos; hinge with one heavy 

 cardinal tooth in upper valve, opposite socket in lower valve; interior 

 white with tinting of exterior color; two muscle scars, simple pallial 

 line; margins finely crenate, closely approximate. 



Found adhering to shells of Atrina rigida, Area zebra and A. 

 notabilis but rarely to other arks, and to dredged fragments of reef 

 rock. Common on valves of Atrina on the beaches; dredged from one 

 to seven fathoms. 



'^^ Gr., ptcro, feather; metis, a part. 



^^ Lat., per, prefix meaning completely, with planus, flat. 



^^ Lat., chama, cockle; congregare, to congregate. 



