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1. Pcctcn circularis ccquisulcatus Carpenter. 58 
Right valve, i.e., the valve having the byssal notch; exterior. 
Dimensions: “Altitude” is distance between the base (B) and the 
apex of the shell or umbo (U) ; “longitude” is the distance be¬ 
tween the anterior extremity (A) and the posterior extremity 
(P) ; “diameter” is the maximum perpendicular distance from the 
plane of the periphery (margin or border) to the top of the 
arched disk, when the shell is lying interior downward; A, an¬ 
terior end; P, posterior end; B, base; U, umbo; U P B A, disk; 
ae, anterior ear or auricle; pe, posterior ear or auricle; bn, byssal 
notch or sinus; ha, byssal area; ps, posterior sinus; sm, sub- 
margins or lateral areas; r, ribs; is, interspaces. 
2. Pecicn circularis ccquisulcatus Carpenter. 58 
Right valve interior. A, P, B, and U as in figure 1 ; hi, hinge 
line; rp, resilial pit; pp, provinculum; cc, cardinal crura; bn, 
byssal notch; cm, ctenolium; as, adductor scar. 
3. Pandora glacialis Leach, 1819.. 89 
Jour. Acad. Nat. Sci., Phila., vol. 7. 
4. Pandora glacialis Leach. 89 
5. Maconia calcarea Gnielin.173 
Puget Sound. 
6. Maconia hrota lipara Dali.171 
Puget Sound. 
7. Pholadidca dancinii Sovverby.-.213 
This is figured as our species has been called this. 
8. Pholadidca darzeinii Sowerby.213 
9. Maconia inquinata Deshayes.172 
Puget Sound. 
10. Maconia incongrua Martens 
Puget Sound. 
170 
