280 University of California Publications in Zoology (Vou. 14 
pears to be unrelated to the distribution of any particular type of 
bottom. 
Range.—Aleutian Islands, Alaska, to Lower California. 
Macoma yoldiformis Carpenter 
Plate 25, figure 6 
Macoma yoldiformis Carpenter (1863), p. 639; (1865a), p. 55; Dall (1990b), 
p. 309; Arnold, R. (1903), p. 165, pl. 16, fig. 6. 
Description.—Arnold’s (1903) description of this species is as follows: 
“*Shell small, subelliptical, compressed, very thin and fragile; umbones 
slightly posterior to center; anterior end evenly rounded, longer than posterior 
side, which is very faintly folded, biangular and more cuneiform; surface 
smooth, except for very fine incremental lines; ligamental area scooped out 
about one-half length of posterior end; teeth very small.’’ 
Length, 16 to 22 mm. 
Occurrence —At stations D 5785* (2), D 5786 (1), D 5789 (1, 1). 
This bivalve has not been reported from this region by earlier 
collectors. It is restricted to the collections from the open ocean. A 
single lying specimen was dredged by the ‘‘ Albatross’’ in 46 fathoms 
on a bottom of fine dark green sand. Shells were dredged at two 
other stations at depths of 39 and 40 fathoms. 
Range.—Strait of Juan de Fuca, Washington, to San Diego, Cali- 
fornia (Arnold). 
Macoma secta (Conrad ) 
Plate 25, figure 8 
Tellina secta Conrad (1837), p. 257. 
Macoma secta, Arnold, R. (1903), p. 164, pl. 16, fig. 5; Dall (1900b), p. 309. 
Description—This species was originally deseribed by Conrad (1837) as 
follows: 
‘‘Shell triangular or subelliptical, equilateral, thin, smooth and polished, 
covered with a very thin shining yellowish epidermis; umbonial slope angulated; 
posterior extremity broadly and obliquely truncated; cartilage short, thick, 
inserted on an elongated oblique rib-like callous; margin beneath the cartilage 
with an ovate gape, appearing as if cut or broken; color white within and 
without.’’ 
Carpenter reports this species from the Farallones. It is abundant 
along the beaches on the open ocean both north and south of the 
Golden Gate. No specimens were obtained by the Survey. 
Range.—Vancouver Island to Gulf of California (Dall). 
