_Hab._ San Pedro, 60; San Diego, 16 dead on beach; Santa Barbara, 4 dead, in 16-20 fms. _Cooper_. As I have seen no complete list of the very numerous fossil species of this genus, it appears allowable, rather than risk a synonym, to name this graceful shell after its discoverer. Genus? MESALIA, Gray. _? Mesalia tenuisculpta_, Cpr. n. s. State Collection, No. 666 _a_. ? M. t. tenui, regulariter turritâ, fusco-cinereâ; anfr. nucl. lævibus, normalibus, apice acuto; norm. viii. rotundatis, suturis impressis; lirulis spiralibus; haud extantibus, plus minusve distantibus, irregularibus cinctâ quarum anfr. primis duæ anticæ majores; lirulis circa basim rotundatam obtusis, subregularibus; rugulis incrementi irregularibus, interdum decussantibus; aperturâ subrotundatâ, peritremati haud continuâ; labro acuto, postice flexuoso; labio tenui. Long. 0·28, long. spir. 0·18, lat. 0·10, div. 15°. _Hab._ S. Diego; 4-6 fms., 15, alive. _Cooper_. Intermediate in character between _Mesalia_ and _Fenella_. Genus ISAPIS, H. & A. Adams. _Isapis obtusa_, Cpr. n. s. State Collection, No. 682. I. t. “_I. fenestratæ_” indole simili, sed magis elongatâ, subnitente, pallide rosacea; vertice nucleoso decliviter immerso, celato; anfr. norm. postice subplanatis, suturis obtusis; costis tumentibus rotundatis circ. vii., suturas et umbilicum minorem versus obsoletis, plus minusve extantibus; interstitiis parvis, irregularibus, haud decussatis; peritremati continuo, labro tenui, secundum costas variantes undulato; labio medio calloso. Long. 0·23, long. spir. 0·09, lat. 0·16, div. 60°. _Hab._ S. Diego, 10 fm.; Sta. Barbara, 20 fm.; _Cooper_. The fortunate discovery of some perfect young specimens displays a nucleus so like _Odostomia_ that, despite the resemblance of the shell to _Fossarus_, which has a tuberoid nucleus, it most probably belongs to _Pyramidellidæ_. Genus RISSOINA, D’Orbigny. _Rissoina interfossa_, Cpr. n. s. State Collection, No. 387, _b_. R. t. satis magnâ, crassâ, albâ, satis turritâ, conspicue sculptâ; marginibus spiræ rectis, vertice mamillato; anfr. nucl. ?.. [detritis]; norm. vii. tumidis, angulatis, suturis angulatim impressis; carinis spiralibus validis, in spirâ ii.; alterâ posticâ interdum intercalante; anfr. ultimo duabus quoque peripherialibus, quintâ axim circumeunte; costis radiantibus validis, extantibus, circ. xiv., ad suturas contiguis, liris regularibus spiram ascendentibus, ad intersectiones carinarum nodulosis, ad peripheriam continuis; interstitiis quadratis, alte infossatis; aperturâ ovatâ. Long. 0·26, long. spir. 0·18, lat. 0·10; div. 28°. _Hab._ Catalina Is. 8-10 fm. 4; San Diego 1; Monterey, (var.) _Cooper_. Genus RISSOA, Freminville. _Rissoa acutelirata_, Cpr. n. s.