Shell conical, thin; spire elevated; one nuclear whorl, smooth, five perfect whorls, subangulated at the margin, obliquely flat above; body whorl very slightly convex at the base; suture strongly impressed; surface marked by revolving tubercular ribs, about eighteen on the body whorl, one broad one on the margin and about eight or nine on the under side; these ribs are less numerous on the preceding volutions, only four can be counted on the upper side of the penultimate whorl; the tubercles are arranged so as to present an irregular quincunx; epidermis a rich coffee brown, darker between the tubercules than on their summits; aperture obliquely quadrangular, outer lip and base acute, internally pearly white, columella bearing two strong folds, the lower one of which borders the truncated end and terminates in a faint tubercular enlargement; behind the columella is a slight groove running from the base to the end of the upper columellar fold. Hab. Monterey, 20 fms. Dr. Cooper. Also fossil, not rare, in the Post Pliocene of San Pedro and Santa Barbara, where some specimens have been found an inch in height. No. 355, Mollusca, Survey Collection. This shell appears to be allied to the genera _Calliostoma_ and _Thalotia_, from which it is separated by the peculiar mouth. In the absence of the operculum, it is impossible to define its position certainly. EMARGINULA, Lam. E. BELLA, G. E. t. alba, oblongo-ovalis, subelevata, antice parum convexa, postice excavata, parte anteriori angustiori; apice excentrico, prominente, parum recurvato; sinu mediocri; costis radiantibus circiter XIX cum costis minoribus interstitialibus irregularitur alternantibus, per lineas concentricas clathratis. Long. ·55, lat. ·36, alt. ·22. Shell oblong oval, somewhat elevated, narrowest anteriorly; apex excentric, posterior, prominent and somewhat recurved; outline in front of the apex slightly convex, from the apex to the posterior margin slightly excavated, sides descending nearly straight; sinus moderate, variable, situated at the extremity of a strong rib; surface ornamented by about nineteen large radiating ribs, with smaller ones interposed, all crossed by moderately prominent concentric ridges; color white. Locality Monterey, Dr. Cooper. “Two dredged dead.” No. 466, Survey Mollusca. GADINIA, Gray. _S. Gen. Rowellia_, Cooper. Animal tentaculis ultra testam porrectis, latis, compressis, margine anteriori rotundato, pectinato; pes mediocris, circularis. Testa _Gadiniæ_ similis. Animal with broad flat tentacles, rounded and pectinated in front, projecting beyond the shell; foot moderate, round. Shell as in _Gadinia_. G. (R.) RADIATA, Cooper.