248 ONITHOCHITON. 



side. Posterior valve having a smooth callus in place of the inser- 

 tion-plate, separated from the eaves by a groove at each side. 



Girdle leathery, closely clothed with microscopic down, clouded 

 brown and whitish. 



Length 42, breadth 20 mill. 



Pitcairn Island, in small hollows, at low water mark (Cuming) ; 

 Raine's Island, Torres Sts., under stones at low water (Ince) ; Wat- 

 son's Bay, N. S. Wales, Australia, at very low tides (Angas.) 



Chiton lyellii SOWB., P. Z. S. 1832, p. 26 : Conch. Illustr. f. 7. 

 REEVE, Conch. Icon., f. 12. Chiton incii REEVE, Conch. Icon* 

 no. 94, t. 16, f. 96; detail fig. 94. Chiton puncticulatus REEVE, 

 Conch. Icon., t. 13, f. 696 and description in part Onithochiton 

 incei ANG., P. Z. S. 1867, p. 223. 



This species differs from O. maillardi in the narrower smooth 

 dorsal areas, the less deep, less regular grooving of the lateral areas, 

 and the shorter and broader posterior valve. It relations to the 

 following species are not clear to me, as I have seen no authentic 

 specimen of the latter. 



Figs. 8, 9 of pi. 55 represent the C. incii of Reeve. 



The Chiton puncticulatus of Reeve seems to have been founded on 

 a specimen of this species and one of Pallochiton lanuginosus ; but 

 Reeve's reference to the punctation seems to apply best to this form. 

 In any case, the name is so ill-defined that it cannot in fairness be 

 used. 



O. QUERCINUS Gould. PI. 55, figs. 12, 13. 



Shell small, depressed, slightly carinateand beaked, ovate, yellow- 

 ish wood or oak color, clouded with olive or dusky slate color at the 

 sides. Lateral areas scarcely raised, but distinctly marked by 

 coarse longitudinal sulci, which are divided by a radiating furrow 

 and sometimes more, and the two portions form somewhat of an 

 angle with each other ; central areas with faint, rugose, longitudinal 

 lines toward the margin, and scattered punctures about the apex ; 

 anterior valve checked with raised spaces formed by concentric and 

 more distant radiating furrows, which become more numerous near 

 the margin ; posterior valve with the umbo nearly terminal, so that 

 the transverse ridge runs nearly parallel to the margin. Marginal 

 ligament broad, yellowish, frosted. (Old.) 



Length 22, breadth 15 mill. 



New South Wales, Australia. 



