230 



shape, which is rather more transverse, lengthening the pallial sinus; 

 in the external granules, which are somewhat coarser ; and in the 

 ligamental pit, which is rather larger, and therefore at a greater 

 angle from the margin. 



6. ? SCROBICULARIA PRODUCTA. 



1 S. t. Candida, tenui, sublaevi, striis incrementi exillimis, confertis ; 

 antice et ventraliter maxime producta; margine anteriore bene ex- 

 curvato, postico valde undato, ventrali subincurvato ; umbonibus 

 prominentibus, appressis ; lunula indistincte impressa ; ligamentis, 

 externo magno, interno minimo, alteri adjacente ; dentibus cardi- 

 nalibus duobus, quarum alter bifidus, alter minimus ; cicatricibus 

 muscularibus, antica elongata, angusta, marginem ventralem ap- 

 propinquante ; postica subquadrata. intus undulata ; sinu pallii 

 maximo ; pagina interna cardinem versus undulata. 

 Long. T45, lat. 1-88, alt. 7 poll. 



Hab. Sinu Califomiensi : legit C. Shipley, Esq. Mus. Cuming. 

 Resembles S. angulata, Chemn., but differs in the great produc- 

 tion of the anterior ventral portion, in the development of the wave, 

 and in the length of the external ligament. This and the following 

 species form connecting links between Scrobicularia and Tellina. 



7. I Scrobicularia biangulata. 



? S. t. suborbiculari, subcequilaterali, convexiuscula, striis concen- 

 tricis vix regularibus, postice undata, angulis duobus subobso- 

 letis ; ligamento externo tenuissimo, in sulcos alte impresso, semi- 

 interne sito ; ligamento interno fossa trigonali scalena sito, alteri 

 adjacente; dentibus cardinalibus in utraque valva duobus, conti- 

 guis, vix radiant ibus ; cicatricibus muscularibus subovalibus, sinu 

 pallii maximo ; alba, intus aureo tincta. 



Long. 1-5, lat. 1*78, alt. *8 poll. 



Hab. Sta. Barbara ; legit T. Nuttall, Esq. Museo suo. 



Differs from S. producta in form and texture, and also in the 

 comparative size of the external ligament, which in this species is 

 situated in a semi-internal furrow. 



8. Donax semistriatus. 



D.t.parva, valde transversa, tumidiore ; parte superficiei antica 

 Icevi, nitida; reliqua concentrice sulcata, sulcis impressis, inter- 

 dum bifurcatis ; striisque radiantibus evanescentibus, sulcos punc- 

 tantibus ; sulcis in parte postica valde cxlatis ; aureo-fuscus, ad 

 umbones rubro-fuscus radiatus ; margine simpliciter crenulato. 

 Long. -4, lat. 8, alt. -2 poll. 

 Hab. in Sinu Califomiensi. Mus. Cuming. 



Somewhat resembles D. pulchellus, Hani., but differs in the 

 markings, the anterior third of the surface being quite smooth, while 

 the remainder is furrowed with rather distant concentric lines, end- 

 ing suddenly, and slightly indented by evanescent striulse. 



9. DlPLODONTA SUBQUADRATA. 



D. t. subquadrata, valde inccquilaterali, antice brevi ; tenui, albo- 



