. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. an affinity to the Tunicata by the mode of respiration. This in- teresting worm was discovered by Delle Chiaje, .and its organization and development have been recently investigated by Al. Agassiz and Kowalevski [more recently by Bateson, Q. J. Mic. Sci. 1884] (fig. 241). The most inte- resting point about this form is the structure of its larva, which renders its relationship to the Echinodermata probable. The larva was described by J. Miiller asTornaria, and was regarded by him as an Echi
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. an affinity to the Tunicata by the mode of respiration. This in- teresting worm was discovered by Delle Chiaje, .and its organization and development have been recently investigated by Al. Agassiz and Kowalevski [more recently by Bateson, Q. J. Mic. Sci. 1884] (fig. 241). The most inte- resting point about this form is the structure of its larva, which renders its relationship to the Echinodermata probable. The larva was described by J. Miiller asTornaria, and was regarded by him as an Echi- noderm larva. It FIG. 241.—Young BaJanogtosstm, strongly mngnifled. Pr, Pro- Joes in fac£ possess boscis, the numerous branchial slits are visible. a double band of cilia, like Bipinnaria. Of these two rows of cilia, one, the praeoral, forms a ring round the pne-oral lobe, while the other is larger and runs in a more longitudinal direction so as almost to join the former near the apical pole. There is also a transverse pra^-anal ring of cilia (fig. 242, a, b). Internally a diverti- culum of the ar- chenteron gives rise to an independent sac forming the water-vascular sys- tem, while two FIG. 242, a, l.—Tomarla larva (after E. Hetschnikoff). a, Seen ,. from the side; 6. from the dorsal surface. O, mouth; A, Palrs OI diverticula anus; S, apex, W, rudiment of water vascular system'; C, furnish the first heart; P, P', peritoneal sacs. rudiments of the body cavity. A pulsating heart is developed from a thickening of " The History of EalanoRlossus and Tornaria," Memoirs of the American Acadt'mij of Arts anJ Sciences, Vol. IX., 1873. E. Mulsrlmikoff /, wissensck. Zool,, Tom XX., 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 Claus, Carl, 1835-1899; Sedgwick, Adam, 1854-1913; Sinclair, F. G.
Size: 1240px × 2015px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1800, bookcollectionbiodiversity, bookdecade1890
