82 HALIOTIS. 



H. RUFESCENS Swainson. PI. 20, fig. -11. 



Shell large, heavy and solid, oval, not very convex ; sculpture 

 consisting of unequal spiral cords and threads and wide low radiat- 

 ing waves ; color dull red ; holes three or four. 



The shell is very large, sometimes attaining a length of 9 inches ; 

 it is thick and heavy, covered outside with a thick brick-red layer 

 which projects at the edge of the lip forming a narrow coral-red 

 edge. The spiral cords are unequal in size, and finer than in H. 

 fulgens; the waves of the surface are large and oblique. Below the 

 row of holes there is a depression, followed by a low ridge bearing 

 usually large obtuse tubercles. The spire does not project above 

 the general curve of the back. Inside the nacre is lighter than in 

 either H. fulgens or H. eorrugata, and the play of tints not so much 

 broken. The colors are chiefly pink and light green, with here and 

 there a small area of prussian blue. The muscle scar is large, pecul- 

 iarly and variously striped with olive-brown, green and blue; a 

 portion of it is roughened by coarse raised cords which take a 

 spiral direction. The columellar plate is rather narrow, its lower 

 part sloping inward somewhat. Perforations large, somewhat 

 tubular, 3 or 4 open. 



Length 185, width 150, convexity 40 mill. 



Length 235, width 185, convexity 58 mill. 



Mendocino Co., to San Nicholas Island, California. 



H. rufescens SWAINS., Catalogue of the rare and valuable shells 

 which formed part of the collection of the late Mrs. Bligh ; appen- 

 dix, p. 2 (1822). REEVE, Conch. Icon., f. 6. SOWERBY, Thes. 

 Conch., t. 5, f. 35. WEINKAUFF, Conchyl. Cab., p. 69, t. 27, fig. 1. 

 ? H. ponderosa ADAMS, Amer. Journ. Sci. and Arts, Second Ser., 

 vi, p. 138, 1848. 



This is the Red Abalone of commerce, the nacre of which is used 

 for the manufacture of buttons, for inlaying, etc. The animal is 

 dried by the Chinese in California and used for food. 



The H. ponderosa of Adams is probably a form of this species. 

 The original description is as follows : 



Shell ovate, convex, ponderous, with coarse, unequal incremental 

 striae and concentric ridges (not folds), and a few broad low tuber- 

 cles on the ridges ; spire elevated, subterminal ; four perforations 

 open, the inner one very large; exterior surface brick red; inner 

 surface elegantly iridescent with innumerable shades of delicate red, 

 purplish-red, and green. 



Length 8 2 in.; breadth 6fiii.; depth within 3iin. 



