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. The chordates. Chordata. Ichthyopsida 4.39 cyclostome hag (Myxine) and the teleost "stargazer" (Astroscopus). Also the dipnoan has the '"lobe-fin'' characteristic of crossopterygians. It seems likely, therefore, that the two groups were closely related at their beginnings, since which the crossopterygians have become nearly (or quite?) extinct and the dipnoans have been reduced to three sur- viving genera. On the ground that the choanae of crossopterygians imply possession of lungs, the Dipnoi and Crossopterygii may be in- cluded together under the name Choanichthyes, a divisi

. The chordates. Chordata. Ichthyopsida 4.39 cyclostome hag (Myxine) and the teleost "stargazer" (Astroscopus). Also the dipnoan has the '"lobe-fin'' characteristic of crossopterygians. It seems likely, therefore, that the two groups were closely related at their beginnings, since which the crossopterygians have become nearly (or quite?) extinct and the dipnoans have been reduced to three sur- viving genera. On the ground that the choanae of crossopterygians imply possession of lungs, the Dipnoi and Crossopterygii may be in- cluded together under the name Choanichthyes, a divisi Stock Photo
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Contributor:

Library Book Collection / Alamy Stock Photo

Image ID:

RJ4JP5

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7.1 MB (345.6 KB Compressed download)

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Dimensions:

1785 x 1400 px | 30.2 x 23.7 cm | 11.9 x 9.3 inches | 150dpi

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. The chordates. Chordata. Ichthyopsida 4.39 cyclostome hag (Myxine) and the teleost "stargazer" (Astroscopus). Also the dipnoan has the '"lobe-fin'' characteristic of crossopterygians. It seems likely, therefore, that the two groups were closely related at their beginnings, since which the crossopterygians have become nearly (or quite?) extinct and the dipnoans have been reduced to three sur- viving genera. On the ground that the choanae of crossopterygians imply possession of lungs, the Dipnoi and Crossopterygii may be in- cluded together under the name Choanichthyes, a division of Osteichthyes. Electric Organs Stories have been told of a curious mishap which may be suffered by horseback riders while fording streams in Brazil or other tropical parts of South America. For no obvious reason, the rider may be plunged into the water by sudden panic or even collapse of the animal under him. The cause of the mishap is mere contact with a harmless- looking eel-like fish. But mere contact suffices to allow the fish to. rio. ."539. Electric organs. (Left) Electric ray. Torpedo: dorsal view; electric organs exposed by removal of skin and superficial tissue. (Right, above) Electric eel, Electrophorus (Gymnotus): caudal location of electric organs indicated by solid black. (Right, below) Stereogram showing relations of eel's electric organs to caudal mus- cles and skeleton. (.4) Anus; (Au) Eye; (DM, DM1) dorsal muscles; (E, El) electric organs; (Ft) ventral fin; (//) skin; (K) gill-clefts; (LH) hemal canal; (S) cranium; (Sep) connective-tissue septum; (Sp) spiracle; (VM, VM1) ventral muscles; (WS, WSl) vertebral column. (Courtesy, Wiedersheim: "Grundriss der vergleichenden Anatomie der Wirbeltiere, " Jena, Gustav Fischer.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Rand,

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