170 Mr. E. A. Smith on Molhisca from the 



Kistna delta, lat. 15° 43' 30" N., long. 81° 19' 30' E., in 678 

 fathoms, living examples. 



In the left valve within the keel which marks off the elon- 

 gate lunule is a second keel, forming, as it were, an inner 

 lunule. This feature is wanting in the opposite valve. The 

 delicate external ligament is supported bj thin reflexed 

 nymphjB, that in the left valve jutting out behind like a 

 lateral tooth. The single cardinal in this valve is triangular, 

 acute above, and fits in between the two divergent teeth in 

 the right valve. 



The dead specimens from 128 fathoms have a pale pinkish 

 tint; but this is probably due to staining after death. 



24. Cuspidaria (^Myonera) caduca. (PI. V. figs. 9, 10.) 



Testa fragilis, longe rostrata, alba, epidermide tenuissima induta, 

 concentriee subfortiter plicata,striisque incrementi minutis sculpta; 

 margo dorsi anticus leviter arcuatus, vix declivis, posticus valde 

 incurvatus ; margo anterior rotundatus, ventralis paulum con- 

 vexus, prope rostrum parum inflexus ; umbones mediocriter pro- 

 minentes, postice inclinati ; area dorsalis antica elongata, Isevis, 

 postica lanceolata, usque ad extremitatem rostri extensa, carina 

 filiforme prope umbones marginata ; carina secunda similaris in 

 utraque valva ab umbone breviter postice producta ; cardo eden- 

 tulus ; fossa Hgamenti parva, postice declivis. 



Longit. 32 millim., alt. 14, diam. 10. 



Hah. Andaman Sea, in 188-220 fathoms. 



The plicEe are rather acute, somewhat irregular near the 

 middle of the valves, and are attenuated at the commence- 

 ment of the rostrum, upon which they become mere stride. 



In general external appearance this species considerably 

 resembles C. chinensis^ Gray. It is, however, not so high, 

 the rostrum is longer, the texture of the shell much thinner, 

 and the strong posterior tooth of the right valve is wanting. 



25. Cuspidaria {Cardiomya) Alcocki. (PI. V. fig. 8.) 



Testa paulo insequivalvis, tenuissima, subglobosa, mediocriter longe 

 rostrata, alba, subpellucida, autice oblique truncata, inferne 

 rotundata, postice infra rostrum baud profunde sinuata ; valvae 

 supra dimidium posticum carinis conspicuis arcuatis acutis quatuor 

 aliisque paucis minoribus interjectis ornatae, ante carinas radiatim 

 tenuissime liratae, lineisque incrementi subcanceliatoe ; rostrum 

 supra levissime incurvatum, extremitatem versus angustatum, 

 liris tenuibus 4-5 radiantibus in utraque valva instructum ; 

 umbones parvi, contigui, incurvati ; dens cardinalis unicus pone 



