PANAMIC-PACIFIC PELECYPODA 221 



Genus ANODONTIA Link, 1807 

 Type species by monotypy, A. alba Link {Venus edentvla Linne, 

 Gmelin, 1792, but not of Linne, 1758 {chrysostoma Philippi). 



Shell rounded, globose, thin, concentrically striate; anterior and pos- 

 terior dorsal areas present or obsolete. Lunule narrow and deep, confined 

 largely to the right valve; no escutcheon. Ligamental scar deeply inset. 

 Hinge edentulous or with subobsolete remnants of the teeth only. Lower, 

 inner section of the anterior adductor scar long and narrow, lying above 

 the pallial line. Ventral margin entire. 



Identification of Anodontia alba is fixed by Link's reference to Venus 

 edentvla Linne in Gmelin (p. 3286) which is the West Indian shell com- 

 monly known as A. chrysostoma (Philippi). This is not the Venus edentvla 

 Linne, 1758 which according to Hanley is a similar Oriental species. (See 

 Dillwyn, p. 202, No. 100.) 



Two subgenera. 



I, Dorsal areas weak or obsolete. 



Subgenus Anodontia, s.s. 



II. Dorsal area sharply defined, depressed. 



Subgenus Lissosphaira, new subgenus 



Anodontia (Anodontia) edentuloides (Verrill) Plate 30, figures 1-lb 



Loripes edentuloides Verrill, 1870, Amer. Jour. Sci., ser. 2, vol. 49, No. 146, p. 226 La 



Pa2 — J. Pedersen. One specimen. 

 Lucina edentuloides (Verrill), Dall, 1901, Proc. U. S. Nat. Museum, vol. 23, No. 1237, 



pp. 802, 803. 

 Anodontia edentuloides (Verrill), Grant and Gale, 1931, Mem. San Diego Soc. Nat. 



Hist, vol. 1, p. 292. — Hertlein and Strong, 1946, Zoologica, vol. 31, pt. 3, p. 



117.— Durham, 1950, Mem. Geol. Soc. America, No. 43, p. 75, pi. 18, figs. 11, 16. 



Shell often large, relatively thin, subglobose, and convex with sub- 

 central beaks. The surface is marked with irregular lines of growth and 

 submicroscopic radial striae may also be seen. Verrill gave the following 

 dimensions for the type specimen. Length 1.65, height 1.50, and breadth 

 1.10 inches. 



Verrill described this shell as subglobose and more swollen than L. 

 edentvla {z=alba Link), the Caribbean species, its apex more prominent and 

 curved, and the lunular region more deeply excavated. The ligament is shorter 

 and its supporting plate is not so stout, its inner edge but little elevated 

 above the ligament groove. 



Specimens in the U. S. National Museum have a white surface covered 

 with thin patches of a dirty gray periostracum and a banded sculpture of 

 wrinkled concentric growth lines set off by deep marks of resting stages. 

 Interior white, the zone within the pallial line chalky or with a finely 

 punctated calcareous coating. The largest specimen in the U. S. National 

 collection measures about 65.6 mm. in length. 



Range — Gulf of California. 



Subgenus LISSOSPHAIRA, new subgenus 

 Type species Anodontia s-pherica (Dall and Ochsner). 



