80 



American Seashells 



Figure 26. Various shapes of bivalves, a, sp'mose. (Echmochauia calif ornicaDaW); 

 b, quadrate (Arcopsis adamsi E. A. Smith); c, orbicular or circular (Divaricella); 

 d, rostrate {Niiciilmm hamata Cpr.); e, trigonal {Crass'mella); f, fan-shaped or 

 pectinate {Aeqziipecten irradiaiis miiplicostata Dall); g and h, obliquely ovate and 

 aequivalve {Crenella cohmibiana Dall); i, elongate {Ensis directiis Conrad); j, 

 mussel-shaped (Modiolus viodiohts Linne); k, ovate {Spisiilci poJynyrua Stimpson). 



