So different in sculpture from _S. pretiosa_ and other species with which it agrees in shape, that there will be no difficulty in recognizing perfect specimens. _Scalaria subcoronata_, Cpr. n. s. State Collection, No. 393, _a_. S. t. compactâ, haud elevatâ, albâ; anfr. x. rotundatis, parum attingentibus; costis circ. xiii. acutissimis, expansis, vix reflexis, postice attingentibus, lineis margini spiræ dextro parallelis spiram, ascendentibus, t. adolesc. postice vix coronatis, adultâ simplicibus; aperturâ subcirculari, umbilico nullo; sculpturâ spirali nullà. Long. 0·45, long. spir. 0·29, lat. 0·22, div. 38°. _Hab._ Monterey; _Cooper_. Like _S. communis_, jun., but with the upper whorls slightly coronated. _Scalaria crebricostata_, Cpr. n. s. State Collection, 393. S. t. gracili, tenui, albâ; anfr. x. rotundatis, haud attingentibus; costis circ. xv., acutis, reflexis, vix attingentibus, lineis irregulariter spiralibus ascendentibus; costis juxta suturam eleganter coronatis; sculpturâ spirali, nisi striulis interdum exillimis, nullâ; aperturâ rotundatâ; umbilico nullo; operculo normali, dense corneo. Long. 0·70; long. spir. 0·52, lat. 0·18, div. 26° _Hab._ Monterey, San Pedro, _Cooper_, common. = “Scalaria, unique” Mus. Cum. No. 32. Somewhat resembles _S. tenuis_, Sby., but is not so turrited. Genus OPALIA, H. & A. Adams. _Opalia spongiosa_, Cpr. n. s. O. t. turritâ, parvâ, albidâ, marginibus spiræ rectis; anfr. ix. subplanatis, suturis impressis; costis undulantibus circ. xiii., plerumque (nisi ad suturas crenulatas) obsoletis; totà superficie lineis punctorum creberrimis, spiralibus, punctis creberrimis, minutis, altissimis; circa basim imperforatam costa anticâ latissimâ, spirali; aperturâ ovatâ, valde callosâ; operculo aurantiaco, paucispirali. Long. 0·36, long. spir. 0·26, lat. 0·12, div. 20°. _Hab._ Monterey, _Cooper_. From shell washings. The solitary specimen has the general aspect of _O. granulosa_ on a very small scale. _Opalia retiporosa_, Cpr. n. s. State Collection, No. 1014. O. t. “_O. bullatæ_” formâ simulante, sed sculpturâ omnino diversâ; anfr. nucl. ?... (decollatis); norm. vii. subrotundatis, suturis impressis; costis radiantibus rotundatis, subarcuatis, haud varicosis, circ. xiv., super suturas tenue continuis; anfr. ult. seriebus nodulorum spiralibus irregularibus, vice costarum, instructâ, peripheriâ tuberculosâ; totâ superficie retiporosâ, interstitiis alte interpunctatis, punctulis minutissimis, confertissimis; basi vix costatâ, à serie nodulorum angulatâ; aperturâ rotundatâ; peritremati continuo, varicoso; labro haud sinuato; operculo? paucispirali. Long. 0·28, long. spir. 0·20; lat. 0·10; div. 20°. _Hab._ Catalina Island; 3 dead in 40 fm.; _Cooper_.