294 AXEL A. OLSSON 



Genus CHIONE Megerle von Muhlfeld, 1811 

 Type species by original designation, Gray, 1847, Venus dysera Chem- 

 nitz ( = Venus cancellata Linne). Recent, along the the east coast of the 

 United States, south of Cape Hatteras, and through the West Indies, Carib- 

 bean, to Panama and Brazil. 



Shell ovate to trigonal, solid, convex, or somewhat compressed, typi- 

 cally with a strong, cancellate sculpture, particularly over the umbones, 

 formed through the intersection of concentric raised lamellae and radial 

 riblets. Lunule cordate or lanceolate, bordered by an incised line, its sur- 

 face sculptured with radial riblets and crowded concentrics. The escutcheon 

 is large and flat, narrowly lanceolate and nearly as strong in each valve, 

 set apart sharply by an angled edge. The hinge is provided with three 

 cardinal teeth in each valve of which the right, anterior and the central 

 cardinal teeth are large. The right, anterior cardinal tooth is always small, 

 and in some cases, it is represented only by the thickened edge of the ad- 

 jacent cardinal socket. The pallial line is almost entire, the sinus is small. 

 The lunular and ventral margins of the valves are finely crenulated. 



Chione is easily distinguished by its solid, trigonal shell and also by its 

 small, anterior cardinal tooth in the right valve and by its small, poorly 

 formed pallial sinus. Most species have a cancellate sculpture, especially 

 over the surface of the umbones. 



Key to subgenera of Chione 



I. Surface sculpture cancellate, the radial and concentric elements of 

 nearly equal strength and distribution. 



Subgenus Chione, s.s. 



II. Surface sculpture formed by concentric folds, the radial elements much 

 weaker. 



1. Concentric folds large, coarse, flattened or rounded in the midzone, 

 often thinner and lamellar on the ends. 



Subgenus Lirophora 



2. Concentrics formed by wavelike undulations, strong and even on the 

 umbones, weaker and subobsolete ventrally, never foliaceous on the 

 sides. 



Subgenus Iliochione 



Chione (Chione) compta (Broderip) Plate 41. figure 4; 



Plate 51, figures 6, 6a; Plate 84, figure 1 



Venus compta Broderip, 1835, Proc. Zool. Soc. London, p. 43, (Sechura). — Sowerby, 

 1853, Thes. Conch., vol. 2. p. 710, pi. 154, figs. 32, 33, 34.— Reeve, 1863, Conch. 

 Icon., vol. 14, Venus, pi. 13. fig. 48. 



Chione meridionalis I. S. Oldroyd, 1921, Nautilus, vol. 34, No. 3, p. 93, pi. 4, figs. 3, 4 

 Peru. 



Chione compta (Broderip), Dall, 1909, Proc. U. S. Nat. Museum, vol. 37, No, 1704, 

 pp. 158, 267.— Olsson. 1924, Nautilus, vol. 37. p. 129. 



Chione {Chione) compta (Broderip), Dall, 1902, Proc. U. S. Nat. Museum, vol. 26, 

 No. 1312, p. 393; Maxwell Smith. 1944, Panamic Marine Shells, p. 61, fig. 778.— 

 Hertlein and Strong, 1948, Zoologica, vol. 33, pt. 4, p. 182. — Parker, 1949, 

 Jour. Paleont., vol 23. No. 6, p. 581, pi. 89. fig. 3; pi. 90, figs. 6, 8.— Hertlein 

 and Strong, 1955, Bull. Amer. Mus. Nat. Hist., vol. 107, art. 2, pp. 192, 193. 



Shell large (length up to about 60 mm.), solid and heavy, rounded, 

 trigonal, compressed. Sculpture is composed of strong, evenly spaced (about 



