8o Palaeontographica Americana 8o 



PI.ATE VI 



Figure Page 



1. Area limula Conrad 27 



South Carolina, probably Pliocene; erect, heavy form, with long hinge- line. 

 This shows the strong, v-shaped teeth. 



2. Area limula Conrad; South Carolina, probably Pliocene; exterior of a heavy valve 

 with long hinge-line and straight posterior margin. This figure shows the charac- 

 teristic even, parallel, cross markings between the ribs. 



3. Area lirnula Conrad; Pliocene of the Croatan Bed, North Carolina; interior of a 

 lighter valve with the typical angle in the upper part of the posterior margin. The 

 teeth are somewhat worn. 



4. Area limula Conrad; Pliocene of the Croatan Bed, North Carolina; X 2; figured to 

 show the form and neat sculpture of the young. 



5. Area limula Conrad; Miocene of Curry, North Carolina; interior of a thin, worn speci- 

 men with the posterior margin nearly at right angles to the hinge-line. 



6. A rea ponderosa Say 28 



Recent from Long Key, Florida. 



7. The same, interior of the left valve. 



8. Umbonal view of the same. 



9. Area poiderosa Say; Pliocene of the Croatan Bed, North Carolina. This form is 

 larger than the recent A. ponderosa and some authors place it in A. limula. It is 

 intermediate between the two species. 



10. Area ponderosa Say; Pleistocene of New Orleans, Louisiana. 



11. Area reversa Gray 29 



Recent from Panama. This west coast species is figured to complete the series 

 showing the posterior shortening and change in the cardinal area of A^oitia as out- 

 lined on p. 29. 



12. Umbonal view of the same. The bare part of the cardinal area forms a narrow 

 strip directly between the beaks. The ligament is entirely anterior to the beaks. 



