REPORT ON THE LAMELLIBRANCHIATA. l75 



usculus. Umbones parvi, acuti, paulo supra lincam cardinis producti. Pagina interna 

 baud nitida, punctis paucis profundis sparsis, sulcoque obbque irregulari in medio notata. 

 Cardo in valva dextra dentc primario infra apicem munitus, dente lateraU antico 

 elongate, margine exteriori sulco profundo sejuncto. Cicatrix antica superne latiuscula, 

 inferne angustata, producta, postice irregulariter ovabs. Ligamentum internum, 



Tbis species is only a trifle longer tban higb, roundish, roundly sbouldered above, 

 only moderately convex, fairly strong, not quite equilateral, white, and scvdptured with 

 fine closely packed concentric lirse which become attenuated and crowded at the sides. 

 In the grooves between them are innumerable very fine radiating lirae which produce a 

 punctured appearance. Down the posterior side of the valves is a faintly impressed ray 

 which is so inconspicuous that it is only seen in certain lights. In front of the beaks is 

 a small but rather deep lunule, shaped not unlike a short spear-head. The front dorsal 

 margin is a little concave and sloping, the posterior being less oblique, longer and 

 straighter. The umbones are small, fairly sharp, but slightly curved over at the tip, 

 and only a little elevated above the dorsal line. There is a single small tubercular 

 cardinal tooth under the beak in the right valve under examination, which is all that is 

 at present known of the species, and the anterior side exhibits a long but not much raised 

 lateral tooth, separated from the outer margin by a deepish groove. The ligament 

 appears to be totally internal, and contained in a furrow beneath the posterior dorsal 

 edge. The dull interior exhibits deep scattered punctures and a strongly marked 

 irregular impressed line extending obliquely from above the posterior muscular scar to 

 below the anterior one. The latter is oval at the upper part, but narrowed and produced 

 downward within the deeply impressed pallia! line, the former being also somewhat oval 

 in form. 



Length 14^ mm., height 13f, probable diameter of the perfect shell 8. 



Habitat. — Port Jackson, New South Wales, in 6 to 7 fathoms. 



Lucina cristata, n. sp. (PI. XIII. figs. 3-3a). 



Testa compressiuscula, tenuis, a^quilateralis, superne breviter rostrata, antice rotundata, 

 postice subquadrata, albida, lii-is concentricis tenuibis confertis postice lamellatis (lamellis 

 impressioni radianti interruptis) instructa, in regione lunulse impressa. INIargo dorsi 

 anticus obliquus, valde excavatus, posticus Eequaliter declivis, rectiusculus. Umlwnes 

 producti, acuti. Dens primarius unicus valv^e dextrae parvus, laterali utrinque 

 inconspicuo, remoto. 



This species belongs to the typical section of the genus Lucina, characterised by 

 possessing primary and lateral teeth and by the concentric nature of the sculpture. 



