82 COLLEOXIONS FROM MELANESIA. 



of tie girdle. On parting the valves a feature is at once discovered 

 in the posterior one which enables us to distinguish the species : 

 in this the margin is very much thickened within, of a dark brown 

 colour, smooth, flattened, and destitute of teeth, whilst in C. spiniger 

 the latter are strongly developed and coarsely striated. The colour 

 of the interior also difiers : C. incanus is stained with dark brown, 

 the centre of the valves exhibiting a large defined black-^brown mark 

 over the jugal sinus, the laminae of insertion being whitish. The 

 central valves have a single, very smaU slit on each side, and the 

 front one has about nine : the former, with the exception of the 

 seventh, are broadest across the posterior margin, as is also the case 

 in the closely allied West-Indian C. piceus, whilst in O. spiniger 

 the greatest diameter is across the laminse of insertion in front of 

 the notch. The jugal sinus appears to be rather deeper than in the 

 latter species. The specimens from Stewart Island, presented to 

 the British Museum by Mr. C. TraiU, agree in all respects with this 

 species ; the form, sculpture, and the insertion-plates are quite the 

 same. 



114. Chiton (ScliizochitoiL) incisus. 



Ohiton incisus, Sowerby, Proc. Zool. Soc. 1841, p. 61 ; Reeve, Conch. 

 Icon. fig. 43. ^ 



Chiton elongatus, Heeve, I. c. figs. 40 a, h. 



Schizochiton incisus, Oray, Froc. Zool. Soc. 1847, p. 169 ; Shuttle- 

 worth, Bern. Mittheil, 1853, p. 68 ; H. ^ A. Adams, Genera Sec. 

 Moll. vol. i. p. 477, pi. 54. figs. 6, 6 a. 



Hah. Island of Zebu, Philippines {Cuming) ; Eaines Island, 

 Torres Straits (Ince) ; Clairmont and Bird Islands, N.E. Australia 

 (Coppinger). 



The mantle is thick, of a somewhat spongy texture, alternately buff 

 and dark brown, the latter colour falling opposite the middle of the 

 valves and forming interrupted irregular narrow stripes. The spines 

 upon it are very short, scattered, and of two colours, brown and 

 white. The raised ridges, generally six in number on the terminal 

 , valves, but sometimes varying to seven or eight, and two on the 

 central ones, are remarkable in being studded with minute blackish 

 beads. The longitudinal fine ridges are peculiarly flat-topped, 

 those on the central areas being straight, whilst on the lateral areas 

 and the front valve they are wavy or zigzag. The lamina of inser- 

 tion in the front valve is thin, externally striated, with six notches 

 corresponding to the radiating costae on the outer surface. In the 

 central valves the lamina is considerably produced in front, with a 

 single small slit on each side ; in the last valve it is thickened 

 posteriorly, interrupted in the middle by a large sinus, is coarsely 

 striated on the outside, and is slit in three or four places. The in- 

 terior of the valves is greenish, stained with brown in the middle. 



