210 TONICIA. 



T. CONFOSSA Gould. PI. 57, figs. 33-36. 



Shell oblong, solid, elevated, the side-slopes straight, dorsal ridge 

 carinated. Ashy white, delicately maculated with various shades of 

 reddish and purple-brown, the darker color irregularly tessellating 

 the posterior margin of each valve. 



The median valves are moderately beaked ; the lateral areas a 

 little raised, and posteriorly and on the diagonal are very peculiarly 

 sculptured with transverse narrow ledges, like the edges of shingles 

 imbricating from the outer margin of the valve upward ; median por- 

 tion of the lateral areas smooth, dotted in a widening band ivith eyes. 

 Central areas peculiarly marked with sparsely scattered subtriangular 

 pits, in some places arranged in irregular transverse rows. Anterior 

 valve having radiating series of ^-shaped imbricating large scales, 

 alternating with narrow bands sparsely dotted with eyes. Posterior 

 valve having the prominent mucro near the posterior end, the slope 

 behind it vertical, in front of it horizontal ; a narrow band of eye 

 dots is behind each diagonal, and they are very sparsely, scattered 

 over the rest of the posterior area. 



Interior white. Sutural plates separated by a moderate sinus, 

 which is delicately denticulate except in the second valve. Anterior 

 valve having 8, median 1, posterior 15 slits; the teeth sharply and 

 deeply pectinated outside; posterior teeth somewhat directed for- 

 ward, deeply pectinated, the slits rather shallow. Eaves narrow, 

 slightly projecting downward near the teeth, and very narrowly 

 grooved just outside of them. 



Girdle blackish-brown, rather fleshy, nude. 



Length about 18, breadth 11 mill.; divergence 120. 



Fiji Is. 



Chiton confossus GOULD, Proc. Bost. Soc. Nac. Hist, ii, p. 143 

 (July, 1846) ; Expedition Shells, p. 5 ; Wilkes' Expl. Exped. Moll., 

 p. 327, atlas f. 434, a, b, Otia Conchologica, p. 5. Chiton (Lucia) 

 confos*us GOULD, Otia, p. 242. Lucia confossa GOULD, Proc. Bost. 

 Soc. viii, p. 283. Lucilina confossa DALL. 



The prominent, posterior mucro, and the peculiar sculpture 

 render this species easily identified. It belongs to that numerous 

 East Indian group (see p. 206) characterized by a rather swollen 

 posterior or post-median mucro, forward-tending posterior teeth, and 

 by the generally punctured grooves of the surface-sculpture ; but in 

 this species the character of the sculpture is unique in the total 

 obsolescence of concentric or forwardly converging riblets on the 



