. Chordate anatomy. Chordata; Anatomy, Comparative. HEPTANCHUS - AN ELASMOBRANCH „.Aii^,e^d,^_^__. Fig. 17.—Types of three sub-classes of fishes—Heptanchu,s, an elasmobranch; Polypterus, a crossopterygian ganoid; and Scomberomorus, a teleost. (Redrawn after Dean.) Class Pisces Fishes are vertebrates with usually scaly skins, permanent gills, and paired fins. The heart is two- or three-chambered. The skeletons may be cartilaginous or bony. Gill-apertures number four to seven pairs. Dorsal and ventral spinal nerves join to form mixed trunks. Sympathetic ganglia are differentiated. The liver has
. Chordate anatomy. Chordata; Anatomy, Comparative. HEPTANCHUS - AN ELASMOBRANCH „.Aii^,e^d,^_^__. Fig. 17.—Types of three sub-classes of fishes—Heptanchu,s, an elasmobranch; Polypterus, a crossopterygian ganoid; and Scomberomorus, a teleost. (Redrawn after Dean.) Class Pisces Fishes are vertebrates with usually scaly skins, permanent gills, and paired fins. The heart is two- or three-chambered. The skeletons may be cartilaginous or bony. Gill-apertures number four to seven pairs. Dorsal and ventral spinal nerves join to form mixed trunks. Sympathetic ganglia are differentiated. The liver has at least two lobes. Of special interest are the orders of fishes which are believed to be near the line of ancestry of land animals. Probably cartilaginous forms like the Elasmobranchs (sharks and skates) were the common stock from which the remaining orders of fishes were evolved. Their gills are not covered by an operculum; their skull is devoid of covering membrane bones; their intestine has a spiral valve. The dogfish Squalus (Fig. 16) is a familiar 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 Neal, Herbert V. (Herbert Vincent), 1869-1940; Rand, Herbert W. (Herbert Wilbur), 1872-1960. Philadelphia : P. Blakiston's Son & Co.
Size: 2275px × 1098px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookpublisherphi, booksubjectanatomycomparative
