ISCHNOCHITON. 91 



of the posterior valve rather acute, in front of the middle ; posterior 

 slope concave. 



Interior whitish or bluish, marked at the sinus with blue-green, 

 and posteriorly with rose ; the tail valve having a conspicuous black 

 crescent in the middle. Anterior valve having 10-12, central 1, 

 posterior valve 10-13 slits; teeth sharp; eaves narrow, solid. 



Girdle indistinctly tessellated with purplish on a paler ground, 

 covered with large, convex, closely and deeply striated solid scales 

 (fig. 74). Length 28, breadth 14 mill. 



Port Jackson, Australia. 



Chiton divergens REEVE, Conch. Icon. t. 8, f. 44. Ch. proteus 

 REEVE, I. c., t. 18, f. 111. Lepidopleurus proteus ANGAS, P. Z. S. 

 1867, p. 222. Itchnochiton divergent and Isch. proteus CPR., MS., 

 Isch. intricatus and Isch. intricandus CPR., MS., olim. 



This species differs from /. longicymba, haddoni and fruticosus in 

 the very much larger convex scales of its girdle. It has the lateral 

 areas much as in I. fruticosus, but the median portion of the cen- 

 tral area is more distinctly patterned, and the jugum is subcar- 

 inated. It varies greatly in coloring, and usually has some rose- 

 pink inside. 



/. divergens has been erroneously united to fruticosus by Angas 

 and by Haddon. It should be understood that all of the detail 

 drawings of the girdles are drawn to exactly the same scale; if this 

 be considered, the student need not hesitate in identifying the pres- 

 ent species. 



I. FRUTICOSUS Gould. PL 23, figs. 78, 79, 80. 



Shell oblong, moderately highly arched, the back rounded, not 

 carinated. Surface lusterless and showing distinct, irregularly 

 radiately roughened lateral areas. Color usually grayish or light 

 green, becoming olive-green or brown toward the sides, and more 

 or less spotted with blackish. 



The lateral areas are raised and irregularly sculptured 

 with a varying number (3-6) of bifurcating subnodose 

 radiating riblets, the posterior one of which is transformed 

 into a series of nodes ; the other riblets often much interrupted 

 (fig. 80), but sometimes nearly continuous; intervals between 

 the riblets are finely granulated. The central areas are either 

 minutely and evenly shagreened in the middle, much as in I. longi- 

 cymba, except that the granules are more distinctly arranged into 



