Report on the zoological collections made in the Indo-Pacific Ocean ...

80 COLLECTIONS FROM MELAN-ESIA.being only 14 millim. in length. The number of radiating ridgesin the terminal valves varies considerably : the type has ten inthe front one, and nine in the posterior ; the single specimen fromPort Molle has the same number in front, but one less behind ; athird 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 theouter ctrxemities. The longitudinal thread-like lira3 are rathergranular through being connected with the still finer cross raisedlines ; they are fairly regular upon the greater part of the surface,but down the centre form an irregular network, not unlike thereticulation of a thimble. The interior of the valves is for the mostpart pale greenish white, but towards the straight posterior marginof the central ones a buff tint prevails. The lamina of insertion inthe front valve is divided (a single specimen only has been examined)by eight minute notches into nine subequal squarely-cut curvedteeth, together forming a festooned semicircle ; from each slit afeeble groove runs to the vertex corresponding to an external rib.The central valves have a single notch on each side immediatelybeneath the termination of the anterior of the two external ridges.The lamina is turned outward at this point and also at the otherrib, forming a little festoon. The last plate has nine notches, onecorrespoudiijg to each rib, with a single (probably unusual) exception,where there are two. The vertex in this valve is central. Thescales of tlie girdle are excessively minute, densely crowded, hardlyvisible under an ordinary lens, and in alternate Hght and dark patches.111. Chiton (CallistocMton) coppingeri. (Plate VI. fig. E.)Shell elongate, greenish white, stained with a dark green colouralong each side near the girdle, with a paler indistinct stripe oneach side of the central line, the apex of the valves being somewhatlivid. Central valves with a straight posterior margin, arched, withonly the faintest indication of a carina at the vertex. Lateral areassomewhat raised, with two radiating rows of coarse transverse rugae,of which the hinder or marginal are the largest. The surfacebetween them is finely granular. Central areas convercd with amore or less criss-cross granulation, the granules at the centre beingvery minnte, and gradually increasing in size towards the sides,where there is very little of the criss-cross arrangement seen at thevertex, but rather a longitudinal disposition of them. The frontvalve is minutely granulated and has about twenty fine radiatingridges, here and there some of them bifurcating near the circumference.Posterior valve rather large, concave behind the subcentralmucro, in front of which the surface is sculptured in the samemanner as the front of the central valve, as is usual with most, ifnot all, Chitons. The posterior half is finely grained and sparselycovered with pustules of different shapes and sizes, the coarsestbeing near the margin and the smallest near the centre. The insertionalplates are thin, with twelve slits in the last, at unequal