A treatise on malacology; or, Shells and shell fish . erous plaits, however, clearly show it is a Har-pula. Another, our H. lyriformis, is the only recentvolute whose spire is longer than the aperture; and athird aberrant type, the H. hullata, stands at the con-fines of this genus, and forms a passage to the next. (97.) VoLUTiLiTHEs, SO far as is yet known, is agenus found only in a fossil state; unless, indeed, Vo-luta nucleus Lam., peculiar to the Australian seas, beconsidered as coming within its limits: it exhibitsnone of the delicate plaits on the pillar of Harpula ; sothat one half of it
A treatise on malacology; or, Shells and shell fish . erous plaits, however, clearly show it is a Har-pula. Another, our H. lyriformis, is the only recentvolute whose spire is longer than the aperture; and athird aberrant type, the H. hullata, stands at the con-fines of this genus, and forms a passage to the next. (97.) VoLUTiLiTHEs, SO far as is yet known, is agenus found only in a fossil state; unless, indeed, Vo-luta nucleus Lam., peculiar to the Australian seas, beconsidered as coming within its limits: it exhibitsnone of the delicate plaits on the pillar of Harpula ; sothat one half of its characters belong to that genus, andthe other half to this. The typical characters of Volu-tilitlies have already been detailed (92.) ; and as we shallparticularly notice the subordinate types hereafter, wemay pass onward to the next group. {9^^ The last of the primary divisions is the Aus-tralian genus ScAPHELLA ; the best known type beingthe Scaphella undulata {fig. 11. a). All of these hithertodiscovered, are natives of the South Pacific We are not aware that any of these shells have an epi-dermis, and their uniform smoothness leads us to con-clude they are partly covered by the dilated lobes of the 108 SHELLS AND SHELL-FISH. PART I. mantle, as in the Olhnn(P. This, in fact, is the only genuswhich is neither spinecl, muricated, nor spire (6) is conic and somewhat short; the whorls ofthe apex are scarcely papillose ; while the inner marginof the lip is considerably thickened. The plaits on thepillar, as to number, are by no means constant, even inthe same species ; in general, there are four, but the lastis always the smallest. Sometimes, however, the pillar,at this part of the aperture, is thickened, and there arefive or even six plaits confused and irregular*, as in S,papillaris (Jig. 12. «). This latter type is remarkable for
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectmollusks, bookyear184
