Boone, Mollusca, Cruises of "Ara" and "Alva" 303 



one of the smallest shells measures : long diameter, 15 millime- 

 ters ; short diameter, 18 millimeters, and altitude, 6 millimeters. 

 Shell solid, wide-oval, approaching subcircular, elevated, sub- 

 conical, apex erect, slightly posterior to the anterior third, surface 

 variously sculptured by thirty to forty moderately strong, radi- 

 ating ribs, of somewhat irregular width, which vary from strongly 

 ribbed, closely scale-grained to nearly smooth; the apical area 

 frequently eroded in large specimens with ribs remaining only 

 on the outer half to two-thirds of the surface. Colour ashen- 

 brown with several wide concentric dark brown zones, or uni- 

 formly brownish ashen, radiately streaked with deep brown al- 

 ternating with ashen, or with oblique brown streaks. Interior 

 opalescent milky white with varying lilac to rosy tints to dark 

 brownish gray with opalescent lilac tones. Muscle-scar pearly 

 gray to snowy white. Margin crenulate, brownish or alternately 

 maculated ashen and brownish, the darker spots corresponding 

 to the dark ribs of the exterior surface. 



References: Patella aenea, Martyn, Thomas, Universal Con- 

 chologist, 1784, vol. I, p. 17. — Reeve, L., Conch. Icon., 1854, 

 f. 9. — Smith, E. A., Philosoph. Trans. Roy. Soc. London, 

 1879, vol. CLXVIII, p. 179. 



Patella gaudichaudi, DE Blainville, H. M. D., Diet. Sci. Nat. 

 Paris, 1825, t. XXXVIII, p. 93. 



Nacella aenea, Pilsbry, H. A., Man. Conch., 1891, vol. XIII, pi. 

 15, figs. 5, 6, pi. 45, figs. 22-23. 



Patella aenea variety magellanica, Gmelin, J. F., Syst. Nat., ed. 

 XIII, p. 3703.— Reeve, L., Conch. Icon., 1854, fig. 19.— 

 Pilsbry, H. A., Man. Conch., 1891, vol. XIII, p. 119, pi. 44, 

 figs. 9-17, pi. 43, figs. 1, 6. 



Patinella magellanica, Dall, W. H., American Journ. Conch., 

 1871-72, vol. VII, p. 273, pi. 15, fig. 24 (soft parts and den- 

 tition) . 



Patella atramentosa. Reeve, L., Conch. Icon., 1854, fig. 41. 



Patella venosa. Reeve, L., loc. cit., fig. 18. 



Patella chiloensis, Reeve, L., loc. cit., fig. 98. 



Patella meridionalis, Rochebrune, de, A. T., et Mabille, J., Bull. 

 Soc. Phil. Paris, 1885, ser. 7, t. IX, p. 109 ; Mission Scientif . 

 du Cap Horn, Zool., 1891, t. VI, p. 94, pi. 5, fig. 4. 



