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Cardiidae 



The veliconcha shell is longitudinally oval and equivalve. The anterior end is 

 narrow and slightly elongate; the posterior end obtuse and broad. The ventral 

 margin is round. The anterior shoulder is equal to, or slightly longer than the 

 posterior. The umbones may be high and round or low and broad. The shell 

 is slightly inflated. The hinge comprises a row of small sharp teeth on the right 

 valve and corresponding sockets on the left valve. Flanges are situated on the 

 left valve and crests on the right. Both anterior and posterior lateral teeth are 

 present. The ligament is posterior. Eyes are absent. The pallial line is distinct. 

 Keenocardium californiense (Deshayes) is found in Peter the Great Bay 

 and the larva is described below. 



Tellinidae 



The shell is equivalve. The veliconcha shell is transversely oval. The shell is 

 inequilateral. Although both ends are roundish, the anterior end is ventrally 

 produced and often longer than the posterior. The shoulders are long and slope 

 steeply. The umbo is initially round but later becomes knob-shaped. The 

 provinculum consists of a row of small rectangular teeth. As the larva grows, 

 special teeth develop in the anterior part of the provinculum. The lateral hinge 

 system is present and consists of alternate crests and flanges — anterior crest 

 and posterior flange on the right valve and anterior flange and posterior crest 

 on the left valve. The ligament is median. Eyes are absent. 



Macoma balthica (Linne) (see below). Peromelia venulosa (Schrenck) 

 (larva not described). Macoma incongnia (Martens) (larva not described) and 

 Macoma orientalis Scarlato (larva not described) inhabit Peter the Great Bay. 



Veneridae 



The shell is equivalve. The veliconcha shell is irregularly rounded and almost 

 equilateral. The anterior margin is slightly more pointed and longer while the 

 posterior margin is broader and shorter. The shoulders are long, straight, and 

 sloped. The umbones are high, broad and roundish. The hinge system is of two 

 types. In members of the genus Venenipis, starting from the end of the first 

 week of life, several small indentations (teeth) develop on the prodissoconch; 

 these do not develop in larvae of the genus Venus. In some species of the genus 

 Venus, weak lateral processes appear, while in others it is difficult to see any 

 hinge structures. The lateral hinge system consists of flanges and crests — 

 flanges on the left valve and crests on the right. In some cases the hinge shows 

 the presence of special teeth. The ligament is posterior. Eyes are absent. 

 These species are found in Peter the Great Bay: Callista brevisiphonata 



