MARINE MOLLUSKS — MACGINITIE 177 



Young specimens were taken as follows: 1 (slightly over 3 nun. 

 long) at 152 feet on Oct. 14, 1949; 1 (9 mm.) at 138 feet on Aug. 1, 

 1950; 1 (9 mm.) at 151 feet on Aug. 5, 1950; 2 (5.5 mm. and 11 mm.) 

 at 175 feet on Oct. 14, 1949; 1 (15 mm.) at 184 feet on Aug. 30, 1949; 

 3 (13, 16.5, and 19 mm.) at 125 feet on Sept. 9, 1948; and 1 (19 mm.) 

 at 120 feet on Aug. 8, 1949. 



Other material examined: Numerous specimens from localities 

 ranging from the mouth of the Mackenzie River to Point Barrow and 

 south and east to the southern coast of Washington; several from 

 the Atlantic area. 



Discussion: The shells of this species, at least those from Point 

 Barrow, are very brittle and often crack while in the trays, pieces 

 even breaking off entirely. They vary in color from a rosy gray to 

 an olive tan, even on the same shell; some show zigzag markings of 

 rose, others are nearly a solid color — grayish tan, for instance. The 

 lines of annual growth are usually darker in color than the remainder 

 of the shell (pi. 26, fig. 5). The siphons, foot, and mantle edge are 

 reddish brown on a cream background. 



Three shells from Point Barrow, measuring 47, 53, and 54 mm., 

 show growth ridges indicating that they are at least 6 years old. 

 What may be called secondary growth ridges, indicating a temporary 

 cessation of growth, are about as prominent as the yearly growth 

 lines, making the determination of age difficult. One shell 54 mm. 

 in length appears to be 9 or 10 years old, but may be only five. 



Distribution: Throughout the Arctic; from the Pacific area south 

 to Puget Sound, and Hakodate, Japan; from the Atlantic area south 

 to Cape Cod; and from Finmarken and Iceland. 



Suborder Teleodonta 



Family Tapetidae 



Genus Liocyma Ball, 1870 



Liocyma Jluctuosa (Gould, 1841) 



Plate 23, figures 1-8 



Venus jluctuosa Gould, 1841, p. 87, fig. 50. 



Tapes fluctuosa Gould, 1870, p. 136, fig. 447. 



Liocyma beckii Dall, 1870b, p. 257; 1871, p. 145, pi. 14, fig. 7. 



Liocyma scammoni Dall, 1871, p. 145, pi. 14, fig. 9. 



Liocyma viridis Dall, 1871, p. 146, pi. 14, fig. 8.— Oldroyd, 1924, p. 159, pi. 1, 



fig. 3. 

 Liocyma aniwana Dall, 1907, p. 172; 1925, p. 18, pi. 28, figs. 4, 6; pi. 29, figs. 1, 2. 

 Liocyma schefferi Bartsch and Rehder, 1939, p. Ill, pi. 8, figs. 1, 1 b. 

 Liocyma fluctuosa Morris, 1951, p. 71, pi. 43, fig. 2. 



A total of 42 specimens, including 3 or 4 drilled shells, was col- 

 lected. Six were washed ashore: 1 (12.2 mm. long) on Sept. 12 and 



