. Elements of Comparative Anatomy. 606 COMPAEATIVE ANATOMY. to a Mullerian^ and a secondary archineplinc duct (Fig. 348). The latter serves as the efferent duct of the kidney, or ureter, in the Coecilise, Urodela, and female Anura, while in the males of many of these latter the primary archinephric duct appears to retain its original function. They open independently into the cloaca. MiJELER, W., Das Urogenitalsystem der Cjclostomen. Jen. Zeitsckr. IX.ââ Semper, C, Das TJrogeriitalsystem der Plagiostomen. Arbeiten aus dem zool. Institut zu Wiirzburg, II.âSpengel, J. W., Das Urogenitalsystem de
. Elements of Comparative Anatomy. 606 COMPAEATIVE ANATOMY. to a Mullerian^ and a secondary archineplinc duct (Fig. 348). The latter serves as the efferent duct of the kidney, or ureter, in the Coecilise, Urodela, and female Anura, while in the males of many of these latter the primary archinephric duct appears to retain its original function. They open independently into the cloaca. MiJELER, W., Das Urogenitalsystem der Cjclostomen. Jen. Zeitsckr. IX.ââ Semper, C, Das TJrogeriitalsystem der Plagiostomen. Arbeiten aus dem zool. Institut zu Wiirzburg, II.âSpengel, J. W., Das Urogenitalsystem der Amphibien. Ibid. III. [Balfour, F. M., A Monograph of the Development of the Elasmobranch Fishes. London, 1878.] § 449. The primitive kidney is likewise developed in the Amniota. For some time in development it extends through the coelom, and projects into it from the dorsal wall of this cavity. The archi- nephric duct is again (Fig. S4:Q,iig) the first part to be developed. The urinary canaliculi (u), which form the glandular portion of the organ, open into it. The hinder portion of the primitive kidney, which has always the same function, is well developed even in the Selachii, but still more so in some of the Amphibia; this is effected by the increase in the number of the urinary canals, and by the formation of special efferent ducts. These processes indicate prophetically the relations of these parts in the Amniota. In the Eeptilia the additional por- tion of the urinary canals is directly connected with the hinder portion of the primitive kidney (Lacerta), but it is not connected with it to form the same, but a new organâthe per- manent kidney. For a long time it is present in company with the primitive kidney, but it has its own ducts (ureters), and it takes on the function of the primitive kidney, in proportion as the latter is atrophied, or converted to the purposes of the generative system. In Birds the rudiment of the permanent kidney appears to be formed ind
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