Page 267 - The Freshwater Mussels of Oklahoma

present or occur in groups or regions of the shell
Right valve: the shell on the right when both shells are together with the dorsal portion upward and the
anterior end forward
Sculpture: structures on the shell surface that are usually characteristic of the species
Sulcus: depressed or indented area on the shell surface or area between elevated regions of the shell
Teeth: any protuberance in the dorsal/hinge region of the shell that help interlock the two valves
Umbo (=Beak): raised or inflated area on the dorsal part of the shell that represents the early growth
region
Umbo cavity (= Beak cavity): depression or pocket on the inside of the shell within the umbo (beak)
Valve: one of the two shells of a bivalve mollusk, one of the two shells of a mussel
Ventral: the part of the shell opposite the umbo and hinge ligament
Wing: extension of the shell on the dorsal surface above the hinge area

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