CHAPTER XXII. 



The Peari, Oyster's Representative — The Arks — The 

 Pea-Pod Sheee— Modiola — The Mussees— Capt. Dix- 

 on's Account — River Ceams — Pisidium — Sph^erium — 

 Keeey Sheees— Lucixa— Lazarina. 



'^PHE family of the AviailidcE^ Av-i-cu'-li-dae, which 

 1 in the Gulf of Californiia furnishes the large and 

 beautful Pearl oyster, Meleagrina mai'-garitifera^ 

 Linn., Mel-e-a-gri'-na mar-gar-i-tif-e-ra, is poorly 

 represented on our coast. In the vicinity of Santa 

 Barbara there is a minute, white, oval shell, one- 

 eighth of an inch in length, named Bryophila setosa^ 

 Cpr., Bry-of-i-la se-to'-sa, which belongs to that 

 family. 



Among the Arks, which are so numerous and fine 

 on the Atlantic coast, we also have but few. 



We name first, Barbatia gradata^ Sby.,Bar-ba^-shi-a 

 gra-da'-ta. Height much greater than its length, 

 valves fully arched, somewhat angular, many ribbed. 

 Breadth one-fourth of an inch or more, color, light 

 brown; found under stones; southern. 



Milneria miimna^ Dall," Mil-ner^-i-a min^-i-ma, 

 resembles the last; but is smaller, curved, and marked 

 with fewer ribs. Recurved at the base; often minute. 



Axinea mtermedia^^xo^. ^P^^-vn' -^-d, in-ter-me'-di-a. 

 Shell solid, white, tinged with brown, nearly circu- 

 lar. Inner edge finely crenulated. Pallial line 

 entire; hinge area crescent-shaped and marked by 



