PLATE LXX. 
PAGE 
Figs. 1-4. Spisula (Hemimactra) sunPONDERosA (d'Orbigny) 28S 
1. Profile of hinge from above, left valve: a, anterior lateral; b, 
cardinal tooth; c, accessory lamella; d, spur with part of the 
cavity for the sagittal ligament below it; e, scar of attachment 
of ligament; f. posterior lateral lamina. 70 mm. (After Dall.) 
2. Exterior of right valve. St. Mary's River. x % 
3. Interior of left valve. St. Mary's River. x % 
4. Hinge-plate of left valve: a, dorsal and e, ventral posterior laminae; 
b, ligamentary scar not separated from the pit below by a sep- 
tum; c, spur; f, accessory lamella; i, petaloid cardinal tooth; d, 
anterior lamina with s. absorption scar, from central lamina of 
opposite valve. 70 mm. (After Dall.) 
Figs. 5a, 5b. Spisula (Hemimactra) confrac.a (Conrad) 289 
5a. Exterior of left valve of type specimen. Patuxent River. Acad. 
Nat. Sci., Phila. 
5b. Interior of the same valve. 
Figs. 6a, 6b. Spisula (Hemi]mactra) subparilis (Conrad) 289 
6a. Interior of right valve. Plum Point. U. S. National Museum. 
6b. Exterior of the same specimen. 
