A. t. valde planatâ, ovoideâ, costis concentricis valde distantibus, angustis, undulatis, ornatâ; marg. dors. post. subrecto, ant. concavo, lunulâ longâ, parum impressâ; ventr. satis rotundato; ant. valde rotundato; post. subquadrato; intus, v. dextr., laminâ cardinali planatâ; dent. card. i. inter fossas ant. parvam, post. triangularem, extante; dent. lat. ant. acutiore, satis elongato, post. nullo; cicatr. adduct. ovalibus, posticâ callo definitâ; margine haud crenato; sulco ligamenti externi elongato. Long. 0·33, lat. 0·26, 0·10. _Hab._ Catalina Island, 30-40 fm. _Cooper_. Only dead right valves having been found, it is not known whether this species be an Astarte (according to Messrs. Adams and Hanley) or an abnormal Crassatella. It scarcely differs from the young of _Astarte omalia_, from the Coralline Crag. Genus CARDIUM, Ln. Subg. FULVIA, Gray, 1847, [or Lævicardium? Sw., 1840.] _Cardium (? modestum, var) centifilosum_, Cpr. State Collection 381. C. t. parvâ, tenuissimâ, inflatâ, subquadratim rotundatâ; umbonibus angustis, tumidioribus; marginibus, dorsalibus subalatis, antico et ventrali æqualiter rotundatis, postico vix truncato; totâ superficie, (nisi umbonibus et dorsum versus utroque latere lævibus,) tenue liratâ; liris circ. centum, quoad magnitudinem extantibus, angustis; interstitiis subæqualibus, subquadratis, interdum punctato-decus satis; parte posticâ à lineâ definitâ, lirulis minus conspicuis, laminis concentricis extantibus, crebrioribus eleganter exasperata; intus, dent. card. validioribus, lat. subdistantibus; cic. adduct. ovalibus, haud impressis. Long. 0·51, lat. 0·48, alt. 0·34. _Hab._ (_modestum._) Quelpart Island, China Seas, and Japan; _A. Adams_. (_Centifilosum_.) Monterey, 20 fms. alive; Santa Barbara 1, Catalina Island, 40 fm. _Cooper_. Rounder than C. modestum, _Ad. & Rve._, with fewer and sharper ribs; but the Eastern shells vary, and Mr. Adams considers them conspecific. Genus LEPTON, Turton. _Lepton meroëum_, Cpr. n. s. L. t. parvâ, subplanatâ, Meroæ-formi; transversâ, marginibus omnino excurvatis; antice valde productâ; umbonibus acutis, prominentibus; dent. card. (v. sinistr.) uno, celato; lat. ant. prominente, post. subobsoleto; fossâ cartilaginali angusta; cic. adduct. remotis. Long. 0·11, lat. 0·08, alt. 0·03. _Hab._ San Diego, 1 broken valve among shell washings. _Cooper_. Genus PRISTIPHORA, Cpr.[17] n. g. Syn. _Pristes_, Cpr. Rep. Brit. Ass. 1864, (pre-occupied.) Testa “_Tellimyæ Adamsiorum_” similis; dentibus cardinalibus nullis; lateralibus utrâque valvâ conspicuis, postice elongatis, antice curtioribus, cardinem versus transversim sulcatis; fossâ cartilaginali inter eos sitâ. _Pristiphora oblonga_, Cpr. n. s.