The Cambridge natural history . Fig. 5.âa, A Tectibrau-chiate Oi)isthobrauch,Umlirella m editerra-nca Lam., Naj^les: a,anus ; br, brauchia ; /,foot ; VI, mouth ; rh,liiiuopliores ; sh, shell. B, A Pteroi^od, Jlya-laea tridentata Forsk.,Naples : sh, shell ; I, I,swimming lobes of foot. C, A Nudibranchi-ate Opisthobranch, Ae-olis iMTcgrina, Naples : f, foot; c, cerata. Aplysia, Umhrella, and the whole group of PteroiJoda ; (h) JVudi-hranchiata, or sea slugs, which have no shell and no truectenidia, but breathe either by the skin, or l;)y cerata orpapilliform organs prominently developed on the b
The Cambridge natural history . Fig. 5.âa, A Tectibrau-chiate Oi)isthobrauch,Umlirella m editerra-nca Lam., Naj^les: a,anus ; br, brauchia ; /,foot ; VI, mouth ; rh,liiiuopliores ; sh, shell. B, A Pteroi^od, Jlya-laea tridentata Forsk.,Naples : sh, shell ; I, I,swimming lobes of foot. C, A Nudibranchi-ate Opisthobranch, Ae-olis iMTcgrina, Naples : f, foot; c, cerata. Aplysia, Umhrella, and the whole group of PteroiJoda ; (h) JVudi-hranchiata, or sea slugs, which have no shell and no truectenidia, but breathe either by the skin, or l;)y cerata orpapilliform organs prominently developed on the back: , Aeolis, Dendronotus. (4) The Pulmonata ^ are asymmetrical air-breathing non-. FiG. 6.âExamples of â A, Pulmonata Basommatophora, the common Limnaeaperegra Miill.: e, e, eyes ; t, t, tentacles. B, Pulmonata Stylommatoiihora,Helix hortensis Miill. : e, e, eyes ; t, t, tentacles ; 2^- o, pulmonary orifice (theposition of the pulmonary orifice in Limnaea will be seen by reference toFig. 101). marine Mollusca, generally, but not always, furnished with ashell. The sexes are always united in the same individual, andthe operculum is always wanting, except in Amphihola. They ^ Pulmo, a lunff. 1 ORIGIN OF THE LAND AND FRESH-WATER MOLLUSCA 1 ) are conveniently divided into Stylomviato2:)hora} in which theeyes are at the tip of the upper tentacles, which are retractile{Helix, Limax, Bulimus, and all true land slugs and snails), andBasommatophora, in which the eyes are at the base of thetentacles, which are not retractile (Limnaea, Planorlis, Physa,and all the Auriculidae).Thus we have , . C Polyplacophora Amvhineura i a i i â ^ (^ Aplacophora ,, , , . J rDiotocardia â
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
