175 



perhaps more orbicular ; but on the whole the differences are not 

 enough to warrant a separate description. 



Yoldia obtusa. T. tenuis, glabra, dilute flavo-virens, transversim 

 ovalis vel potius subcrescentica, tumida ; umbonibus parvis ad trien- 

 tem sitis ; extremitate antica acuta ; margine dorsali postica recta 

 demum declivi ; extrem. postica rotundata ; margine ventrali valde 

 arcuata ; area dorsali angusta hand circumscripta ; cardine debili, 

 denticulis anticis 20, posticis 24 instructo. Long. 16; alt. 9; lat. 6 

 millim. Inhabits Hong Kong harbor, in mud, 6-10 fathoms. W. S. 



Generally resembles Y. sapotilla G. but is less attenuated than any 

 species I have seen. 



Nucula parvula. T. minuta, flavescens, ovato-cuneata ; disco 

 glabro, limbo striis exilibus confertis radiato; umbonibus tumidis, 

 post-medianis ; extremitate antica acuta admodum nasuta ; extrem. 

 postica rectangulari ; margine interna crenulatil. Long. 2; lat. 1.5; 

 alt. 1.5 millim. Hong Kong harbor, in 8 fathoms, muddy bottom. 



w. s. 



Allied to N. nana Hinds. 



Nucula (Acilaj insignis. T. magna, solida, oblique ovato-trian- 

 gularis, ventricosa, sulcis e lined mediant divaricantibus interdum 

 prope marginem bifurcatis arata, epidermide olivacea induta; umboni- 

 bus posticis, fere terminalibus, conspicuis ; extremitate posteriori ver- 

 tical}, angulo ventrali obtuso, area dorsali depressa, cristata, vallibus 

 acutis circumscripta ; portione antico ovato : cavositas salmonacea, 

 argentata ; denticulis anticis circiter 20; posticis 10. Long. 15; alt. 

 12; lat. 8 millim. Dredged off the east coast of Japan, lat. 37°, and 

 at Hakodadi. W. S. 



The description of N. mirabilis Hinds would apply in general to this 

 shell ; but in the figure, the postero-ventral junction is more acute 

 angled, and there are angular markings represented at the extremities. 

 In one of our specimens there is a double series of zigzags down the 

 disk. 



Leda custidata. T. parva, olivacea, concentrice sulcata, pyri- 

 formis, antice subglobosa, postice subito contracta, rostrata : umbonibus 

 paulum antemedianis ; area dorsali postica ampla, cristata, carinis sub- 

 marginalibus circumscripta; dentibus cardinalibus anticis 12, posticis 

 14. Long. 7; alt. 4; lat. 3 millim. Inhabits Hong Kong harbor, in 

 mud, 8 fathoms. W. S. 



Approaches nearest to Leda retusa. 



Modiolaria cuprea. T. trapezoidea, ventricosa, tenuis ; epider- 

 mide ochracea ; umbonibus obtusis ; extremitate antica insolite obtusa, 

 fere verticali ; margine dorsali lente arcuata, quoad marginem ventra- 

 lem fere rectam parallela ; extrem. postica obtusa ; valvis absque 



