. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. \\ Buccal Hood Buccal Cirri Dorsal Fin Rays Photoreceptors in Nerve Cord Atriopore \ Ventral Fin \ Gonads r \ V xMetapleural Fold Ventral Fin Rays Notochord Dorsal Fin • Intestine. \ Velur,, d N vv Branchial Bars _. Wheel Organ branchial Clefts j PharynX , Atriopore Anus Caudal Fin Fig. 13. Diagrams of amphioxus. a, side view of the entire animal; b, side view showing internal features, (a, after Kirkaldy.) It is not as a source of Chinese food, however, t
. Biology of the vertebrates : a comparative study of man and his animal allies. Vertebrates; Vertebrates -- Anatomy; Anatomy, Comparative. \\ Buccal Hood Buccal Cirri Dorsal Fin Rays Photoreceptors in Nerve Cord Atriopore \ Ventral Fin \ Gonads r \ V xMetapleural Fold Ventral Fin Rays Notochord Dorsal Fin • Intestine. \ Velur,, d N vv Branchial Bars _. Wheel Organ branchial Clefts j PharynX , Atriopore Anus Caudal Fin Fig. 13. Diagrams of amphioxus. a, side view of the entire animal; b, side view showing internal features, (a, after Kirkaldy.) It is not as a source of Chinese food, however, that the chief interest in amphioxus lies, but because in its development and structure this little animal points the way to the rise of the complicated conditions found in higher vertebrates. It will be necessary later on, when tracing the origin of various vertebrate organs, to go back repeatedly to the stage presented by amphioxus. Amphioxus, or the "lancelet" as it is commonly called, is an elongated, semi-transparent, fishlike animal, two or three inches in length when fully grown, and somewhat pointed at either end, as its Greek name (amphi, both; oxus, sharp) indicates. In habit it is largely sedentary, lying buried in the sandy bottoms with its anterior end projecting. It is a poor swimmer, coming to rest by lying on its side when not burrowing into the sand. At the anterior end, guarding the mouth, is a circle of bristle-like cirri attached to the edge of the buccal funnel within which is a whirlpool of cilia, the "wheel organ," which helps to direct the microscopic food into the mouth (Fig. 13).. 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 Walter, Herbert Eugene, b. 1867; Sayles, Leonard Perkins, 1902-. New York : Macmillan Co.
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Keywords: ., bookcentury1900, booksubjectanatomycomparative, booksubjectverte
