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Show 1877.] COLLECTION M A D E BY H.M.S. 'PETEREL.' 71 12. HIPPONYX GRAYANA, var., Menke. A young shell, apparently belonging to this species, differs from the normal form in being much more coarsely radiately costated; and consequently the crenulation of the basal margin is considerably more conspicuous. 13. RISSOMA STRICTA, Menke. The single specimen from the Galapagos Islands agrees very closely with the description given by Menke (Zeitschrift fiir Malokozoologie, 1850, p. 177). The labrum is very greatly thickened, and the transverse liration is strongly developed around the lower half of the body-whorl. The whorls are ten in number, and have about twenty smooth ribs, which are slightly flexuous on the last. Fig. 25, on plate iii. of Schwartz von Mohrenstein's monograph of the genus, gives a very good representation of this species. 14. TROCHUS (OMPHALIUS) COOKSONI, sp.n. (Plate XI. fig. 7.) Testa valde umbilicata, suborbiculata, levissime conoidea, fusco roseoque variegata, lineis albidis nigro articulatis obscure picta ; anfractus 4\, subleevigati, convexiusculi, striis spiralibus paucis tenuibus insculpti; ultimus superne convexus, infra suturam leviter depressus, ad peripheriam compfanatus, idcirco biangu-latus, basi subjjlanus, tenuissime spiraliter striatus, circa um-bilicum sulco haud prof undo aratus; umbilicus albus, profundus, callo albido, ad basim columellce dentem formante circumdatus ; apertura suborbicularis; columella arcuata, anfractui callo juncta. Diam. maxima 8 millim., minima 7, alt. 4. This shell is deeply umbilicated, elevately orbicular, convex above, only slightly conical and flat beneath ; the last whorl is flattened at its middle ; and this produces a double angulation, which, however, is not very conspicuous ; there is also a faint depression a little below the suture. The coloration of this species is not very definite ; the upper surface is blotched irregularly with pink and brown, and some spiral, articulated lines, the base is a trifle paler ; the only sculpture consists of fine spiral striations, which are most conspicuous on the base • the callus which surrounds the umbilicus is whitish, and terminates in a faint tooth on the columella, and is bordered by a shallow sulcus in the whorl. The columella terminates above in a callosity which extends upward some distance on the whorl, and also spreads out within the aperture. T. occultus of Philippi, bears a faint relationship to this form, hut is more conoid and more strongly sculptured. 15. FISSURELLA OBSCURA, Sowerby. 16. CHITON (LOI-HYRUS) GOODALLII, Broderip. 17. CHITON (LOPHYRUS) SULCATUS, Wood. |