NORTHWEST COAST MARINE SHELLBEARING MOLLUSKS. 13 
Genus YOLDIA Moller, 1842. 
Section MEGAYOLDIA Verrill, 1897. 
YOLDIA THRACIAEFORMIS Storer, 1838. 
Boston Journ, Nat. Hist., vol. 2, p. 122. — Gould, Inv. Mass., p. 97, fig. 66. 
Arctic Ocean to Oregon. Also Atlantic. 
YOLDIA SECUNDA Dali, 1916. 
Proc. U. S. Nat. Miis., vol. 52, No. 2183, p. 398. 
Southeastern Alaska, in deep water. 
YOLDIA BERINGIANA Dali, 1916. 
Proc. U. S. Nat. Mus., vol. 52, No. 2183, p. 399. 
Bering Sea to Anacapa Island, California. 
YOLDIA MONTEREYENSIS Dali, 1893. 
Nautilus, vol. 7, No. 3, p. 29 ; Bull. Nat. Hist. Soc. Brit. Col., No. 2, p. 9, pi. 
2, fig. 16. 
Chirikoff Island, Alaska, to San Diego, California. 
YOLDIA MARTYRIA Dali, 1897. ^ 
Bull. Nat. Hist. Soc. Brit. Col., No. 2, p. 9, pi. 2, fig. 15. 
Kasaiin Bay, Alaska, to Gulf of California. 
YOLDIA VANCOUVERENSIS, Smith, 1880. 
Ann. Mag. Nat. Hist., ser. 5, vol. 6, No. 34, p. 289. 
Vancouver Island (Smith). 
Section YOLDIA, s. s. 
YOLDIA MYALIS Couthouy, 1838. 
Boston Journ. Nat. Hist., vol. 2, p. 62, pi. 3, fig. 7. 
Arctic Ocean to Puget Sound. Also Atlantic. 
YOLDIA COOPERI Gabb, 1865. 
Proc. Cal. Acad. Sci., vol. 3, p. 189; Pal. California, vol. 2, pi. 9, fig. 54. 
San Francisco Bay to San Diego, California. 
YOLDIA LIMATULA Say, 1831. 
Anier. Conch., pi. 12. — Hanlev, Mon. Nuculidae, pi. 1, fig. 9. 
Arctic Ocean to San Diego. Also Atlantic. 
Section CNESTERIUM Dali, 1898. 
YOLDIA SCISSURATA Dali, 1898. 
Trans. Wagner Inst., vol. 3, pt. 4, p. 595. 
Arctic Ocean to Gulf of Georgia. 
YOLDIA SEMINUDA Dali, 1871. 
Anier. Journ. Conch., vol. 7, p. 153 ; Bull. Nat. Hist. Soc. Brit. Col., No. 2. 
p. 8. 
Okhotsk and Bering Seas to Sitka, Alaska. 
YOLDIA ENSIFERA Dali, 1897. 
Bull. Nat. Hist. Soc. Brit. Col., No. 2, p. 9, pi. 2, fig. 4. 
Southeastern Alaska to San Luis Ohispo, California. 
YOLDIA ENSIFERA PLENA Dali, 1908. 
Proc. U. S. Nat. Mus., vol. 34, p. 256. 
San Diego, California. SO fathoms. 
167980— 21— Bull. 112 2 
