EEPORT ON THE LAMELLIBRANCHIATA. 311 



fine concentric lines of gi'owtli, producing, chiefly towards the uml>o, a distinctly 

 cancellated surface. The other valve is much paler than the right, and adorned 

 throughout with numerous fine concentric lirae. The hcaks are acute, converging with 

 slightly concave sides to an angle of aliout 114°. The cars are small, al)Out equal on 

 both sides, feebly sculptured with stria} of growth and oblique at the sides. The 

 posterior of the left valve diflfers from the rest in having a very small sinus where it 

 joins the dorsal slope of the valves. The interior is coloured like the outside very gloss}', 

 and strengthened with about fifteen Avhite radiating lirse which terminate abruptly and 

 extend over the tinted porti(.)n of the valves. Some of them in certain specimens are 

 very short, and are not produced towards the beaks like tlie rest, which gradually 

 attenuate upwards. 



Length 191- mm., height 21-i, diameter 5. 



Habitat. — Station 210, Philippine Islands, in 375 fathoms; blue mud. 



This species is remarkable for the orange colour of the right valve and the fleshy tint 

 of the left, also for the strongisli and abruptly terminating internal lirag. I name it w-ith 

 much pleasure after my late friend Dr. Gwyn Jeffreys, of " British Conchology " renown. 



Amussium tom'.'^i, n. sp. (PL XXIII. figs. 3-Sh). 



Testa parv^a, compressa, tenuis, subpellucida, alba, le\iter injequivalvis, valvaj 

 diverse sculptse, marginil)us superuis levissime concavis. Valva (dextra ?) paulo con- 

 vexior, nitida, iucrementi lineis minime conspicuis sculpta, sinistra lii'is confertis 

 tenuissimis concentricis oruata. xVuriculaj jjarum insequales, postica paulo majore, in 

 valva sinistra striis paucis radiantibus prope marginem obliquum dorsalem signata. 

 Pagina interna nitens, radiis tenuissimis duodenis inasqualibus instructa. 



This species, so far as at present known, appears to he of small size. It is very 

 thin, scarcely gaping at the sides, slightly inequivalve, very much compi-essed, and 

 semitransparent white. The valves are about as long as high, have acute beaks and 

 faintly concave dorsal slojjes, the ajtical angle being of about 105 to 110 degrees. The 

 valve regarded as the right is a trifle deeper than the other, and nearly quite smooth 

 and glossy, exhibiting only the feeblest indications of lines of growth, the left valve, 

 on the contrary, being prettily ornamented with very fine and close-set concentric 

 liraj. The auricles are unequal in size, the posterior being considerably larger, that of 

 the left valve exhibiting a few (two or three) striae near the dorsal slope. The 

 interior is glossy, and strengthened with twelve slender radiating liras, of which the 

 two uppermost are very small and insignificant. 



Length 8 mm., height 8^, diameter 2. 



