171 



subcirculari ; extrern. postica acutiori, obliqua ; ligarnento conspicuo : 

 cavositas ex albo viridans, costa ab umbone usque ad cicatricem 

 auterioreui munita ; margine interiori simpliei ; dente laterali antieo 

 minimo vel obsoleto. Long. 30; alt. 27; lat. 15 milliui. Inhabits 

 Hakodadi Bay, in sandy mud, 8 fatli. "YV. S. 



It has the general aspect of Astarte, with its thick, dark epidermis, 

 but has the hinge of Mysia, subgen. Felania. 



Mysia dolabrata. T. parva, compressa, symmetrica, rotundato- 

 quadrata, flavescens, glabra ; umbonibus medianis, parvis, acutis ; 

 costa, interna intra-umbonali exili, postice submarginali. Long. 10 ; 

 alt. 10 ; lat. 4 inillim. Inhabits Simon's Bay, Cape Good Hope. 

 W. S. 



Generally resembles Felania Senegalensis. 



Mysia figlina. T. oblique rotundata, lenticularis, nitida, con- 

 centrice striolata, pallide argillacea ; umbonibus acutis vix anteniedi- 

 anis ; disco intus calcareo ; dentibus cardinalibus validis ; costa intra- 

 umbonali obliqua, satis conspicua. Long. 18; alt. 16; lat. 6 niillim. 

 Dredged off the east coast of Japan, lat. 37°, in coarse, black sand, 

 20 fathoms. W. S. 



Has a peculiar argillaceous look which may serve to distinguish it 

 from other species. M. dolabrata scarcely differs except in polish, 

 size, and obliquity of beaks. 



Mysia abbreviata. T. tenuis, fragilis, straminea, glabra, subglo- 

 bosa, postice valde truncata, superne compressa ; declivitate umbonali 

 angulata ; antice rotundata ; umbonibus medianis, tumidis, acutis ; 

 lineis increment! conspicuis : cavositas cretacea, citrina. Long. 20 ; 

 alt. 1 7 ; lat. 1 2 niillim. Inhabits Hong Kong harbor. W. S. 



Mysia obliqua. T. parvula, oblique rotundato-ovata, lenticularis, 

 flavescens, zonis incrementi raris ornata ; umbonibus antemedianis ; 

 regione postica latiori, rotundata ; margine ventrali oblique arcuata ; 

 costa interna umbonali tenuissima ; cardine debilisshno. Long. 8 ; 

 alt. 7 ; lat. 3.5 millim. Inhabits Loo Choo. W. S. 



Has no very marked characters, but in general is like a small M. 

 globularis Lk. It is more globose than M. figlina. It is possibly a 

 very small specimen of Diplodonta Koreensis Ad. and Kv. 



Lepton firmatum> T. subtrigona, planata, lactea, subdiaphana, 

 glabra ; umbonibus medianis, baud eminentibus ; margine ventrali 

 fere recta ; pagina interiore subrugosa ; cicatricibus subrotundis ; denti- 

 bus curtis, validis. Long. 5 -\- ; lat. 2 -|- ; alt. 4 niillim. Inhabits sand 

 at low water, Simon's Bay. W. S. 



In shape like L. squamosum, but distinguished by its short, stout 

 teeth. The rugosities are probably caused by a perforating parasite. 



Lepton concentricum.^ T. ovato-triangularis, subplana, con- 

 centrice concinuc Urata (liris acutis), epidermide subrugosa marginem 



