. Journal of morphology . being based on them as to what the con-ditions were. In the adult he comments upon the cartilaginousnature of the operculum (Stapes) and the lack of a stilus (columella). Diemictylus viridescens. Little need be said of the conditions inthis form since in all essentials it resembles Triton closely. In thetransformed salamander (red form) as also in the fully adult (Figs. The Columella Auris in Amphibia. 575 2-3), the operculum is plate-like, of cartilage, having the samerelations to the fenestral margin as in Triton. It is somewhat moremassive; the fenestral margin is
. Journal of morphology . being based on them as to what the con-ditions were. In the adult he comments upon the cartilaginousnature of the operculum (Stapes) and the lack of a stilus (columella). Diemictylus viridescens. Little need be said of the conditions inthis form since in all essentials it resembles Triton closely. In thetransformed salamander (red form) as also in the fully adult (Figs. The Columella Auris in Amphibia. 575 2-3), the operculum is plate-like, of cartilage, having the samerelations to the fenestral margin as in Triton. It is somewhat moremassive; the fenestral margin is cartilaginous only in front andabove where the cartilage extends back to the caudal end of thefenestra. Below, cartilage extends back only as far as the anteriortip of the operculum. A well developed M. opercularis is the larval stage the morphological relations are essentiallythose of Triton lanse, the vestigial plate being somewhat moreclosely joined to the crista semicircularis (Fig. 4, Cr. s.), but its. Fig. 2. Fig. 3. Fig. 2. Diemictylus viridesceus, laud form. , canalis lateralis; ,cavum perilymphaticum; , ductus perilynipliaticus; H., ceratoliyale;Op., operculum; >S(/., os squamosum. Fig. 3. Diemictylus viridesceus, laud form. , caualis lateralis; ,cavum perilymphaticum; , ductus perilymphaticus; H., ceratohyale;Op., operculum ; , recessus perilymphaticus; Sq., os squamosum. ventral edge more evidently outside the membrana fenestrae. At15 mm. in length, neither columella nor operculum have a 17 mm. specimen, the columella is developing upon the fenes-tral membrane in continuity with the fenestral margin above and infront. The operculum is forming on the medial edge of the fenestrain continuity with the cartilage of the capsule. Aside from growthand a more marked differentiation of the operculum, there has beenbut slight change in a larva 19 mm. long. At 37 mm. the operculumand also the columellar plate are well dev
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