208 AXEL A. OLSSON 



D. Dorsal areas weakly developed or obsolete. 



9. Surface almost smooth, the radial elements small. Size small. 



Parvilucina 

 Subgenus HEfiE Gabb, 1866 

 Type species by monotypy or by subsequent designation, Stolizcka, 

 1871, Lucina (Here) richthofeni Gabb. 



Shell similar to Lucina, s.s., solid, globose with well-developed dorsal 

 areas and conspicuous concentric sculpture. Lunule large, deeply excavated, 

 penetrating into the hinge plate and partly effacing the anterior cardinal 

 tooth. 



Lneina (Here) exeavata Carpenter Plate 29, figures 7, 7a 



Lucina exeavata Carpenter, 1857, Cat. Mazatlan Shells, Brit. Mus., p. 98, No. 140 



"Mazatlan" 

 Lucina (Here) richthofeni Gabb, Geol. Sur. California, Palaentology, vol. 2, p. 29. 

 Phacoides {Here) richthofeni (Gabb), Dall, 1901, Proc. U.S. Nat. Museum, vol. 23, No. 



1237, p. 810, pi. 40, figs. 7, 9. 

 Lucina (Here) exeavata Carpenter, Stewart, 1930, Acad. Nat. Sci. Philadelphia, Spec. 



Publ. No. 3, p. 181, pi. 15, fig. 3, pi. 17, fig. 5.— Grant and Gale, 1931, Mem. 



San Diego Soc. Nat. Hist, vol. 1, pp. 290, 291, pi. 14, figs. 2, 5, 10.— Hertlein 



and Strong, 1946, Zoologica, vol. 31, pt. 3, p. 113. 



Shell relatively small (length 25 mm. or less), rounded, globose, nut- 

 shaped. Anterior dorsal area more strongly defined than the posterior, en- 

 closing the deep, penetrating lunule. Surface marked with strong, con- 

 centric ridges, and smaller striae. 



Relatively rare in the Recent. Also reported as fossil from the Oligocene, 

 Miocene, PHocene, and Pleistocene of California. 



Range — San Pedro, California, to Mazatlan, Mexico. 



Subgenus PHACOIDES Blainville, 1825 

 Type species by monotypy, Lucina jamaicensis Lamarck. 



Shell subcircular to subovate, moderately convex and usually of coarse 

 texture, the interior in old specimens become coarsely pustulose. Anterior 

 and posterior dorsal submargins well defined by being more depressed, set 

 off by a groove and a sharp emargination of the shell margins. Cardinal 

 teeth weak or obsolete, the laterals remain strong and distant. External 

 sculpture dominantly concentric, formed by raised lamellae between wider 

 interspaces. 



The name "Phacoides" is in doubtful standing; as pointed out by 

 Iredale, Stewart, and others. It was used in a vernacular sense by Blain- 

 ville for the true Lucinas and not as a newly proposed generic term. The 

 group is well represented in the Caribbean but is not yet known from the 

 Panamlc-Pacific region. 



Subgenus LUCDfOMA Dall. 1901 

 Type species by original designation, Lucina filosa Stimpson. 



Shell large or of medium size, subcircular to suborbicular, equivalye. 

 Dorsal areas strongly depressed. Surface white, with a conspicuous perio- 

 stracum. Sculpture consists of raised, concentric lamellae, generally widely 



