The Cambridge natural history . he right siphon is but sliglitly developed, the left is very long, almost twice as long as theshell (see Fig. Go). The animal, whenunder the water, lengthens its siphon,brings the orifice to the surface, and l<yalternatelyraising and depressing its headproduces in the pulmonary sac movementsof ex- and inspiration; these are repeatedabout ten or fifteen times at regularintervals of from six to eiglit seconds,a method (.)f respiration strongly resem-bling that of the (Jetacea. At the sametime, liranchial respiration takes powdered carmine is added to w
The Cambridge natural history . he right siphon is but sliglitly developed, the left is very long, almost twice as long as theshell (see Fig. Go). The animal, whenunder the water, lengthens its siphon,brings the orifice to the surface, and l<yalternatelyraising and depressing its headproduces in the pulmonary sac movementsof ex- and inspiration; these are repeatedabout ten or fifteen times at regularintervals of from six to eiglit seconds,a method (.)f respiration strongly resem-bling that of the (Jetacea. At the sametime, liranchial respiration takes powdered carmine is added to water,the particles are seen to enter tbe l»ran- Vic. insul- ^.j^-^| ^^^ . ^^^^ i^uAlOlX and paSS out artdii Orb. : A, bivatliiiij, . water; B, Iji-eathing air; Si, l)y the short rigllt siplioll. Sometimes siplion; T, iiii))er : /, lower 4,1 • i • 1 . ,- tentacles; xpalliul ex-^he animal remains under water iorpansion, performing tlie part hours without rising to the Surface to of siplion. (Alter. Fisclier auil Bouvier, x J.). inspire air. In Ialrata (Fig. OG) theliranchia is very large, and projects likea leaf or fan al)ove tlie shell on the left side ; on the correspond-ing position on the rigiit side is a, long filiform appeiulage, wliichsome have regarded as representing the other Ijranchia. 02)isthohra)ifhiata.—A true Inanchia occurs only in the Tecti-1)ranchiata and the Ascoglossa. It lies on the right side, and isusually more or less external, being partly covered sometimes bythe shell (as in UmhreUa, Fig. 5), sometimes Ity a fold of themantle. In the Pteropoda (which are probably derived from theTectibrancliiata), all the Thecosomata, with tlie exception ofCavolinia, have no specialised l)rancliia, but probal)ly respiretbrougli portions or the whole of the integument. In the(rymnosomata an accessory branchia has in many cases Ijeen de-veloped at the posterior end of the body. Fncvmodennon alonelias both lateral and posterior l)ranchiae we
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
