12 ACANTHOCHITES. 



whitish bunches. Length 17, breadth 8 mill. Oran, Algeria, 

 collected by Deshayes' expedition of 1842; types in the Paris 

 Museum. (Rochebr. in Bull. Soc. Philomath. 1881-1882, p. 191.) 



A. DISCREPANS Brown. PI. 4, figs. 80, 81, 82. 



Shell oblong, rather elevated, carinated. Color grayish, variously 

 mottled with dull reddish-brown ; the ridge often marked with lilac 

 or blackish. 



Median valves, when detached, showing a broadly triangular 

 tegmentum, slightly beaked in the middle of the subconcave poste- 

 rior margin, the latero-anterior margin sigmoid, convex at the outer, 

 concave or subconcave toward the anterior termination ; length of 

 tegmentum contained If times in its breadth, except the 2nd valve, 

 which is longer. Later o-pleural areas sculptured with very fine and 

 numerous round flat-topped granules, arranged in curving slightly 

 irregular series, radiating from the beaks. Dorsal area narrowly 

 triangular, elevated at the edges, somewhat convex, finely striated 

 longitudinally. Anterior valve granulated, its lower margin feebly 

 scalloped. Posterior valve with central, slightly projecting mucro ; 

 the tegmentum oval, wider than long. 



Interior white, faintly tinged with blue, and more or less suffused 

 with lilac-pink along the middle of the cavity. Sinus rather deep 

 angular. Posterior valve having no posterior sinus or wave in the 

 insertion-plate, which has the usual single slit on each side, sometime, 

 doubled on one side. 



Girdle broad, grayish, covered with a thick velvety pile, and hav- 

 ing ttffts of white, yellowish or greenish spicules at each suture, with 

 four additional around the anterior valve ; periphery of girdle not 

 furnished with a fringe of spicules longer than those covering the sur- 

 face. 



Length 36, breadth 19 mill. ; divergence 105-115. 



Channel Islands to Morocco and Madeira; Mediterranean and 

 A driatic Seas. Low water to 25 fms., on stones. 



Chiton discrepans BROWN, 111. Conch. Gt. Brit., p. 65, t. 21, f. 20 

 (1827). FORBES & HANLEY, Hist. Brit. Moll, ii, p. 396, t. 58, f.4. 

 SOWB., Illustr. Index Brit. Sh., t. 10, f. 7. JEFFREYS, Brit. 

 Conch, iii, p. 214; v, p. 198, t. 55, f. 4 ; P. Z. S. 1882, p. 667. 

 WEIXKAUFF, Conchyl. Mittelm ii, p. 413. Chiton fascicularis var. 

 major PHIL., Enum. Moll. Sicil. i, p. 108, t. 7, f. 2 ; ii, p. 83. C. 

 fascicularis (part) DESK., in Lam., An. s. Vert. (2), vii, p. 492, and 

 of POT. & MICH., REEVU, Conch. Icon., t. 10, f. 53, PETIT, Journ. 



