The Cambridge natural history . o trace of any inter-mediate forms, and, as a matter of iact, tlie midti])le inanchia is 154 BREATHING ORGANS IN AMPIIINEURA found (Hily in the Ami^hinenra, while one or rarely two (nevermore) pairs of liranchiae, occur, with various important modi-tications, in the vast majority of the Mollusca. Aiivpltineura.—In Chiton tlie branchiae are external, forminga long row of short plumes, placed synnnetrically along each sideof the foot. The numl)er of plumes, at the base of each of whiclilies an osphradial patch, varies from about 70 to as few asG or 7. Aien the plu


The Cambridge natural history . o trace of any inter-mediate forms, and, as a matter of iact, tlie midti])le inanchia is 154 BREATHING ORGANS IN AMPIIINEURA found (Hily in the Ami^hinenra, while one or rarely two (nevermore) pairs of liranchiae, occur, with various important modi-tications, in the vast majority of the Mollusca. Aiivpltineura.—In Chiton tlie branchiae are external, forminga long row of short plumes, placed synnnetrically along each sideof the foot. The numl)er of plumes, at the base of each of whiclilies an osphradial patch, varies from about 70 to as few asG or 7. Aien the plumes are few, they are confined to thepL)steri(jr end, and thus approximate to the form and position ofthe la-anchiae in the other Amphineura. In Chaetoderm<(, thebranchiae consist of two small feather - shaped bodies, placedsynnnetrically on either side of the anus, which opens into a sortof cloaca within which the l)ranchiae are situated. In JSfcomeniathe branchiae are still further degraded, consisting; of a single lT{. Fid. 61.—Terminal portions of the Amphineura, illustrating the grailiial degrailationof the branchiae, and their grouping round the anus in that class. A, Chiton(Uemtarthrum) setulosus Carp., Torres Str.; B, Chiton {Lejjtochiton) benthus Hadd.,Torres Str.; C, Chaetodinnn : D, Xeomenia; a, anus; ///•, br, branchiae; k, k,kidneys ; p, pericardium. (A and B after Haddon, C and D after Hubrecht.) liUMch of tilaiuents lying within the cloaca, while in Froncomcni((there is no more than a few irregular folds on the cloaca-wall(Fig. Gl;. In the Frosohranchiata, symmetrically paired l)ranchiae occuionly in the Fissurellidae, Haliotidae, and Ileurotomariidae, in theformer of which two perfectly equal branchiae are situated oneither side of the l)ack of the neck. These three families takentogether lV)rm the group known as ZygohrancJiiata} In all otherfamilies the asynnnetry of the bod} has prolmbly caused one ofthe branchiae, the right (originally left), to beco


Size: 2790px × 896px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No

Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895