PLATE LXX. 



PAGE 



Pigs. 1-4. Spisula (Hemimactra) suuroNDEROSA (d'Orbigny) 288 



1. Profile of liinge 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; 



&, 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) confraga (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 (Hemimactra) subparilis (Conrad) 289 



6a. Interior of right valve. Plum Point. U. S. National Museum. 

 6b. Exterior of the same specimen. 



