Boone, Mollusca, Cruises of "Ara" and "Alva" 291 



the central areas show faint transverse "growth" lines and minute 

 but regular and numerous punctae, forming a pattern of continu- 

 ous dots. 



Anterior valve: This is finely sculptured, with numerous coni- 

 cal granules, arranged closely in an irregularly radiating pat- 

 tern, these granules being fine near the apex and increasing 

 substantially in size toward the circumferal margin. The sur- 

 face between the big granules is microscopically granulose. There 

 are twenty-one slits present. 



Intermediate valves: These six valves have the jugum mod- 

 erately but definitely elevated and the surface of the central areas 

 is faintly marked transversely by obscure growth lines and is 

 regularly finelj'' punctate, these punctae forming a fine pattern of 

 dots in the interstices between the vague low worn granulations. 

 The lateral areas are but little elevated, each being sculptured 

 with about seven oblique, uneven and unequal rows, composed of 

 low, irregular verrucae, those forming the outermost rows being 

 placed longitudinal with the valve, while those verrucae forming 

 the five intermediate rows have their length parallel the width of 

 the pleural area. The entire pleural surface between these ver- 

 rucae and occasionally of the verrucae also is microscopically 

 granulose. Each intermediate valve has one slit. 



Posterior valve: This has the umbo very near the anterior 

 margin. The surface of this valve, like that of the anterior valve, 

 is finely sculptured with numerous conical granules, arranged 

 closely in irregularly radiating lines, these granules being fine 

 near the umbo and increasing in size toward the circumferal mar- 

 gin, the surface between the verrucae being finely granulose. 

 There are twenty-five slits present. 



Girdle: In the preserved specimens, this is 6 millimeters wide, 

 deep olive green, covered with imbricating scales set in twelve or 

 thirteen rows, of which the median rows of scales are much the 

 larger, the other scales decreasing in size toward both the inner 

 and outer lateral margins. The scales are very convex, the larger 

 ones also being carinate. 



References : Chiton 7narquesanus, Pilsbry, H. A., and Tryon, 

 G. W., Manual of Conch., vol. XIV, Polyplacophora, 1892, 

 p. 170, pi. 36, figs. 98, 99, 100 (Colour plate).— Nierstrasz, 

 H. B., Siboga-Expeditie, monogr. XLVIII, 1905, p. 87. 



