. A manual of zoology. Zoology. Fig. 542. Fig. 543. Fig. 542.—ilouth of Pclromyzou mariinis with horny tcclh and tongue (from Gegenbaur). Fig. 54^—GUI apparatus of f;liiti)iosa latter J. ^liiUer). a, atrium; ah, gill arterj- and gill arch; br, gill sac (the lines show the gills); br', elTerent canal; r, oesophageo-cutaneus duct; </, skin turned away; /, atTerenl gill canal; 0, cesophagus; .^, mouth of atrium; v, ventricle of heart. which contains gills, and the afferent and efferent ducts (fig. 543). These ducts develop separately, and may continue so (BdcUos/oma), but in Pclromyzo
. A manual of zoology. Zoology. Fig. 542. Fig. 543. Fig. 542.—ilouth of Pclromyzou mariinis with horny tcclh and tongue (from Gegenbaur). Fig. 54^—GUI apparatus of f;liiti)iosa latter J. ^liiUer). a, atrium; ah, gill arterj- and gill arch; br, gill sac (the lines show the gills); br', elTerent canal; r, oesophageo-cutaneus duct; </, skin turned away; /, atTerenl gill canal; 0, cesophagus; .^, mouth of atrium; v, ventricle of heart. which contains gills, and the afferent and efferent ducts (fig. 543). These ducts develop separately, and may continue so (BdcUos/oma), but in Pclromyzon the alferent ducts unite to a sittgle tube which opens veutrally in the In Myxiiic (lig. 543) the coirditioris are reversed, the efferent canals of a side uniting to empty tlirough a single external opening. A third name, Monorhina, has been giveir, since these forms, in con- trast to all other vertebrates, have an uiipaired olfactory organ. The single nostril, lying irt the mid line of the head, opens into a nasal sac, from the bottom of which a canal desceirds towards the roof of the mouth, end- ing blindly in Petromyzontes (H^qaeroartia), or penetrating the palate in the Myzontes (H^i^erotretia), so that an inner nasal opening (choana) into the pharynx occurs. A paired olfactory nerve supplies 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
Size: 1207px × 2069px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
