s '» COLLECTIONS PROM MELANESIA. 



being only 14 millim. in length. The number of radiating ridges 

 in the terminal valves varies considerably : the type has ten in 

 the front mie. and nine in the posterior; the single specimen from 

 Port Molle has the same number in front, but one less behind; a 

 third example has seventeen anterior and sixteen posterior ones. 

 The central valves are arched, but exhibit a carina at the vertex. 

 The two radiating costae are sometimes more or less double at the 

 outer etrxemities. The longitudinal thread-like lirae are rather 

 granular through being connected with the still finer cross raised 

 lines ; they are fairly regular upon the greater part of the surface, 

 but down the centre form an irregular network, not unlike the 

 reticulation of a thimble. The interior of the valves is for the most 

 part pale greenish white, but towards the straight posterior margin 

 of the central ones a buff tint prevails. The lamina of insertion in 

 the front valve is divided (a single specimen only has been examined) 

 by eight minute notches into nine suhequal squarely-cut curved 

 teeth, together forming a festooned semicircle ; from each slit a 

 feeble groove runs to the vertex corresponding to an external rib. 

 The central valves have a single notch on each side immediately 

 beneath the termination of the anterior of the two external ridges. 

 The lamina is turned outward at this point and also at the other 

 rib, forming a little festoon. The last plate has nine notches, one 

 corresponding to each rib. with a single (probably unusual) exception, 

 where there are two. The vertex in this valve is central. The 

 scales of the girdle are excessively minute, densely crowded, hardly 

 visible under an ordinary lens, and in alternate light and dark patches. 



111. Chiton (Callistochiton) coppingeri. (Plate YI. fig. E.) 



Shell elongate, greenish white, stained with a dark green colour 

 along each side near the girdle, with a paler indistinct stripe on 

 each side of the central line, the apex of the valves being somewhat 

 livid. Central valves with a straight posterior margin, arched, with 

 only the faintest indication of a carina at the vertex. Lateral areas 

 somewhat raised, with two radiating rows of coarse transverse rugae, 

 of which the hinder or marginal are the largest. The surface 

 between them is finely granular. Central areas convered with a 

 more or less criss-cross granulation, the granules at the centre being 

 very minute, and gradually increasing in size towards the sides, 

 where there is very little of the criss-cross arrangement seen at the 

 vertex, but rather a longitudinal disposition of them. The front 

 valve is minutely granulated and has about twenty fine radiating 

 ridges, here and there some of them bifurcating near the circumfer- 

 ence. Posterior valve rather large, concave behind the subcentral 

 mucro, in front of which the surface is sculptured in the same 

 manner as the front of the central valve, as is usual with most, if 

 not all, Chitons. The posterior half is finely grained and sparsely 

 covered with pustules of different shapes and sizes, the coarsest 

 being near the margin and the smallest near the centre. The in- 

 sertional plates are thin, with twelve slits in the last, at unequal 



