128 THE VOYAGE OF H.M.S. CHALLENGER. 



Venus (Chione) infans, u. sp. (PI. III. figs. 3-36). 



Testa parva, rotuude subtrigonalis, insequilateralis, teuuiter cancellata, alba, interdum 

 fusco obsolete bi-radiata, antice late arcuata, postice angustior, subproducta. Lunula 

 magna, prominens, fusco tincta, elongato-cordata. Area indistincta aliquando 

 fuscescens. Dentes cardinales tres in utraque valva. Margo valvarum intus denticul- 

 atus, postice minutissime. 



This shell is somewhat triangular, the angles being rounded, about as high as long, 

 with a cancellated surface. The cancellation consists of strong radiating ridges, of which 

 those upon the lunule and a few near the j^osterior slope are finer than the rest. These 

 are crossed by regular subequidistant fine concentric lamella having a crenulated aspect, 

 and being but little elevated. The lunule is large in proportion to the small size of the 

 shell, somewhat bulging, distinctly defined, and probably in most instances stained with 

 light brown, especially at the front part. The umbones are rather prominent, well 

 incurved and a little anterior in position. The hinge is composed of three teeth in each 

 valve. Of those in the right the anterior is the smallest, the others being subequal and 

 diverging. The central in the left valve is short, stouter than the anterior, located just 

 beneath the umbo, and inclines a trifle towards the hinder end. The anterior tooth is 

 more slender, diverging much towards the front, being subparallel with the margin, the 

 posterior being still thinner. The posterior dorsal margin in the right valve is grooved 

 to receive a prominent ridge in the left. The denticulation of the margin is coarse along 

 the lunule, fine immediately beneath and at the posterior extremity, and again more 

 strongly developed along the ventral portion. The interior of the valves is glossy, and 

 exhibits the pattern of the exterior cancellation, but only indistinct traces of the muscular 

 scars and pallial sinus are discoverable. 



Length 4 mm., height 3f , diameter 2^. Another specimen is 3^ mm. long and 2f high. 



Habitat. — Station 187, a little to the west of Cape York, North Australia, at a depth 

 of 6 fathoms. Also Station 188, a little further west, at a depth of 28 fathoms. 



Several odd valves of this pretty species were dredged at the above localities, but 

 mostly in a dead chalky condition. In such as are fresh, the colour is more or less trans- 

 parent white, varied with two light brown rays down the central portion of the valves, 

 the lunule and hinder dorsal slope being sometimes tinged with the same colour. The 

 form of the species is high, and the cancellation of the surface comparatively strong, 

 corresponding in this respect with Venus stutclthuryi of New Zealand. 



Venus (Chione) levukensis,n. sp. (PI. III. figs. 6-66). 



Testa insequilateralis, alba, radiatim crassecostata, umbones versus laevigata, inter 

 costas sub-distanter concentrice striata, postice oblique subtruncata, antice angustior, 



