12 RECENT BIVALVE MOLLUSiKS 



Section Yoldia s. s. 



Yoldia myalis Couthouy, 1838. 



Arctic Ocean to Puget Sound. Also Atlantic. 

 Yoldia cooperi Gabb, 1865. 



San Francisco Bay to San Diego, Cal. 

 Yoldia limatula Say, 1831. 



Arctic Ocean to San Diego. Also Atlantic. 



Section Cnesterium Dall, 1898. 



Yoldia scissurata Dall, 1898. 



Arctic Ocean to Sitka. Alaska. 

 Yoldia seminuda Dall, 1871. 



Okhotsk and Bering Seas to Sitka, Alaska. 

 Yoldia ensifera Dall, 1897. 



Southeastern Alaska to San Luis Obispo, Cal. 

 Yoldia ensifera, variety plena Dall, 1908. 



San Diego, Cal., 80 fathoms. 



Section Yoldiella Verrill, 1897. 



Yoldia siliqua Reeve, 1856. 



Norton Sound, Alaska. Also Atlantic. 

 Yoldia intermedia Sars, 1865. 



Bering" Strait and Norton Sound. Circumboreal. 

 Yoldia orcia Dall, 1916. 



Tillamook Bay, Oregon, to San Diego. 

 Yoldia sanesia Dall, 1916. 



Boca de Quadra, Alaska, to Point Conception, Cal. 

 Yoldia oleacina Dall, 1916. 



Arctic Ocean north of Bering Strait. 

 Yoldia capsa Dall, 1916. 



Oiff Tillamook Bay, Oregon, in 786 fathoms. 

 Yoldia cecinella Dall, 1916. 



Aleutian Islands to Gulf of California. 



Section Portlandia Morch, 1853. 



Yoldia glacialis Gray, 1828. 



Arctic Ocean at Point Barrow. Also Atlantic. 



Gcims Pleurodon Wood, 1840. 

 Subgenus Cyrilla A. Adams, 1860. 



Cyrilla munita Carpenter, 1898. 



Santa Barbara Islands to Gulf of California. 



