PANAMIC-PACIFIC PELECYPODA 161 



Nodipecten is a natural group with several species in the Recent and 

 late Tertiary faunas. 



Lyropecten (Nodipecteu) subuodosus (Sowerby) Plate 20, figures 1-lb; 



Plate 21, figures 5, 5a 



Pecten subnodosus Sowerby, IS35, Proc. Zool. Soc. London, p. 109. — Sowerby, 1843, 



Thes. Conch., vol. 1, Pecten, p. 65, pi. IS, figs. 97, 112.— Reeve, 1852, Conch. 



Icon., vol. 8, Pecten, pi. 4, fig. 20. 

 Pecten nodosus subnodosus Sowerby, Maxwell Smith, 1944, Panamic Marin« Shells, p. 



52, fig. 692 D. 

 Pecten (Lyropecten) subnodosus Sowerby, Hertlein and Strong, 1946, Zoologica, vol. 



31, pt. 2, p. 58. 

 Lyropecten subnodosus (Sowerby), Durham, 1950, Mem. Geo). Soc. America, No. 43, 



pt. 2, p. 65, pi. 11, fig. 1. 



Shell large, coarse, the adult often attains a height of 4 to 4^2 inches. 

 Both valves are similar, not strongly convex. Most specimens of the typical 

 form have 10 ribs in the left valve and 11 ribs in the right, counting the 

 deep furrows around the ventral margin. The ribs are as wide as their inter- 

 vals, both covered with a series of close-set, coarse, slightly scabrous radial 

 cords; there are usually a scattering of small or coarse, sometimes hollow 

 nodes or humplike swellings along the summit of the ribs, best developed 

 on the left valve. Color is usually a deep rose-purple or wine red, often 

 lightly or heavily maculated, the variation in color being less than in the 

 Caribbean forms of L. nodosus. Interior of the right valve is usually white 

 with a colored marginal border, the left valve, the same color as the exte- 

 rior but of a lighter shade, merging into white in the umbonal cavity. Ears 

 unequal in size, the anterior larger and longer, that of the right valve with 

 a deep notch. 



Length 95.2 mm., height 93.7 mm., diameter 30.1 mm., length of hinge 

 48 mm. Manta, Ecuador. 



The largest specimen of L. subnodosus seen from Ecuador has a height 

 of about 110 mm. A large specimen of subspecies L. intermedius, recorded by 

 Hertlein and Strong, has a height of 150 mm. 



Northern forms from the Gulf of California have generally one less rib 

 and have been separated as subspecies L. intermedius (Conrad) by some 

 authors. This shell was noticed as variety 1 by Sowerby and shown by his 

 figure 97 in the Thesaurus. It appears to be closely related to nodosus from 

 the Caribbean. Lyropecten nodosus of the Caribbean and Western Atlantic 

 can generally be separated from L. subnodosus by its broader, wider, and 

 more rounded form, has one less rib, and the ribs are more coarsely sculp- 

 tured with heavier, cordlike secondary radials and is more strongly nodose. 



Range — Mexico to northern Peru. Costa Rica: Puntarenas. Panama 

 and the Canal Zone: Bahia Honda and Hannibal Banks (Hertlein and 

 Strong); Venado Beach in the Canal Zone. Ecuador: Santa Elena; Man- 

 glaralto; Punta Blanca; Isla la Plata; Manta. Peru: Mancora; Negritos. 



Lyropecten (Nodipecten) magnificns (Sowerby) Plate 22, figure 1 



Pecten magnificus Sowerby, 1835, Proc. Zool. Soc. London, p. 109, var. a Gallapagos; 



var. b Isla la Plata. — Sowerby, 1842, Thes. Concli., vol. 1, Pecten, p. 65, No. 



60, pi. 15, fig. 114.— Reeve, 1852, Conch. Icon., vol. 8, Pecten, pi. 2. fig. 9. 

 Pecten (Lyropecten) magnificus Sowerby, Grant and Gale, 1931, Mem. San Diego Soc. 



Nat. Hist, vol. 1, pp. 182, 183, pi. 9, fig. 1; pi. 10, fig. 6. 



