. A manual of zoology. XII PHYLUM CHORDATA 3-3 bers of the sub-phylum, and are best regarded as consti- tuting by themselves a division, which, for reasons which will be manifest shortly, is designated Acrania, the rest of the sub-phylum being known as Craniata. A. THE ACRANIA This isolated group, the Acrania, comprises only a single family, the two genera {Sranchiostoma and Asymmctroii) of which are distin- guished from one another by comparatively slight differences. Branchiostoma (more widely known under the name of Amphioxus), the lancelet, is a small transparent animal, occurring in the s
. A manual of zoology. XII PHYLUM CHORDATA 3-3 bers of the sub-phylum, and are best regarded as consti- tuting by themselves a division, which, for reasons which will be manifest shortly, is designated Acrania, the rest of the sub-phylum being known as Craniata. A. THE ACRANIA This isolated group, the Acrania, comprises only a single family, the two genera {Sranchiostoma and Asymmctroii) of which are distin- guished from one another by comparatively slight differences. Branchiostoma (more widely known under the name of Amphioxus), the lancelet, is a small transparent animal, occurring in the sea near the shore and burrowing in sand; its length does not exceed t/orsj* ^Q^m^^^^^ cir /'///l JOP mlpl ai).p â *">&* yenlf cut Kin. -o,. â Amphioxus lanceolatUS. A. ventral: B, side view of the entire animal. an anus; airv. atriopore; cd. f, caudal fin; cir, cirri: dors, f, dorsal fin; dors f. r, dorsal fin-rays; gm, gonads; mtpl, metapleure; myoni, myomeres: âch, notochord; or. hd, oral hood; vent. /, ventral fin; vent. /. r, ventral fin- rays. (After Kirkaldy.) or less than two inches. Tts form will be obvious from Fig. 203. The body is elongated, pointed at either end, and compressed. The anterior two-thirds is roughly triangular in transverse section, presenting right and left sides, inclined towards one another, above, and a convex ven- tral surface. The posterior third is nearly oval in section, the right and left sides meeting above and below in a somewhat sharp edge. Extending along the whole of the dorsal border is a median longi- tudinal fokl, the dorsal fin (dors. /); this is continued round the. 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 Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. New York, The Macmilla
Size: 2085px × 1198px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1900
