. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. KM BR \'(K\7C /)/â : 11:1. 129 Strongly confirmed by the mode of development of the prnemandibular cavities in the Cyclostomes. In these fishes, vox Kupf- FER has shown that they actually appear in the form of a pair of diverticula from the anterior extremity of the archenteron (Fig. ']2). If a comparison be made between Figs. 70 and 72, it will be at once manifest how close the correspondence is Fig. 72. â Horizontal projection of betwee
. Amphioxus and the ancestry of the vertebrates [microform]. Vertebrates; Chordata; Fishes; Ascidiacea; Vertébrés; Cordés; Poissons; Ascidiacés. KM BR \'(K\7C /)/â : 11:1. 129 Strongly confirmed by the mode of development of the prnemandibular cavities in the Cyclostomes. In these fishes, vox Kupf- FER has shown that they actually appear in the form of a pair of diverticula from the anterior extremity of the archenteron (Fig. ']2). If a comparison be made between Figs. 70 and 72, it will be at once manifest how close the correspondence is Fig. 72. â Horizontal projection of between the modi' of de- pharynx and praoral endockrniic exten- 1 . c .\ \ y â sion of a vounir .Immoca-tes planen of Velopment of the head-CaVl- 3.^ ââ,^ reconstructed from a STics of ties in AmphioXUS and in transverse sections. (After Kll'KKK.) I' endodermic e ^tension (pnvorale Endodernitasche). /;;. and m. I'ra-niandibular and niantlilniU).' portions avities. ph. Cavity of pharynx. /, 2, J. First three jiairs of gill-pouches. â KujifTer considers it j)robable that the mandibular as well as the pr;e- mandibular cavities arise from tlie single pair of endodermic diverticula. In the course of the following pages I have referred chiefly to the pr;vmandibular. Ammocoetes. In the Se 1 I . .1 ⢠â¢! *j. ⢠I i;eiiiaiiii lachians the simdarity is ^f iiead-c hardly less striking.** Endostylc and Pigvictit Grannies. In Fio". 64 there is to be cavities alone so as to avoid complica- ^ tions. noticed a vertically placed structure lying in front of and contiguous with the club- shaped gland. It is a tract of very high cylindrical cells forming part of the right wall of the alimentary canal in !l homologised with the praimandibular cavity (see below, V.). Kupffer re<;arils the privmandibular and mandibular heaci-cavities as rudimentary or meta- morphosed gill-pouches. This deduction is entirely foreign to the standpoint which I have adopted. The con
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectfishes, bookyear1894
