Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 Pig. 241.—Young Balanoglotmt, strongly mngnifled. boscis, the numerous branchial slits arc visible. an affinity to the Tunicnta 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
Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 Pig. 241.—Young Balanoglotmt, strongly mngnifled. boscis, the numerous branchial slits arc visible. an affinity to the Tunicnta 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 does, in fact, possess a double band of cilia, like Bipinnaria. Of these two rows of cilia, one, the prpeoral, forms a ring round the pra3-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 prae-anal ring of cilia (fig. 242, a, h). Internally a diverti- culum of the ar- chenteron gives rise to an independent sac forming the water-vascular sys- tem, while two pairs of diverticula furnish the first rudiments of the body cavity. A pulsating heart, is developed from a thickening of Fig. 242, a, h.—Tomiaria larva (after E. Metschnikoff). a, Seen from the side ; b. from the dorsal surface. O, mouth; A, anus; S, apex, W, rudiment of water vascular system; C, heart; P, P', peritoneal sacs. ' The History of Balanoglossus and Toraaria,' Mvmmrs of the American Academy of Arts and Sciences, Vol. IX., 1873. E. MetschnikofiE, Zeitsehr. f. missensch. ZooL, Tom XX., 1870.
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