. Catalogue of the Chaetopoda in the British Museum (Natural History). Oligochaeta; Polychaeta. Gills of A rente0la 59 angles to that in which they are drawn. Tliis ^ill-axis and the three hundred gill-filaments it bears, affording a very large aerating surface, would be a most etiicieut respiratory structure. All the known examples of A. loveni possess typically pinnate gills, practically identical in their form and" details with those of A. cristata. Both types of gill are found in A. marina. The large Laminarian form has pinnate gills similar to those of A. cristata ; the smaller litto
. Catalogue of the Chaetopoda in the British Museum (Natural History). Oligochaeta; Polychaeta. Gills of A rente0la 59 angles to that in which they are drawn. Tliis ^ill-axis and the three hundred gill-filaments it bears, affording a very large aerating surface, would be a most etiicieut respiratory structure. All the known examples of A. loveni possess typically pinnate gills, practically identical in their form and" details with those of A. cristata. Both types of gill are found in A. marina. The large Laminarian form has pinnate gills similar to those of A. cristata ; the smaller littoral form has fruticose gills. The second gill of a littoral example of A. marina, 120 mm. long, is shown in I'l. XIII, Fig. 4o. The gill consists of nine axes, " webbed " at their base, and a tenth is just making its appearance. The longest— dorsal—axis is about 2 mm. in length, and its lateral branches are. Fig. 31.—.4. marina (ivom Wood's HoH), dorsal axis of fifth L'ill. rig. 32.—A. i<u»illa (from I'ualaska). axis of fifth gill. Dorsal typical of those found in this form of gill. The ventral axis is a little unusual in that one of its branches is disproportionately large. A gill-axis from a specimen of A. marina (200 mm. long) from Wood's Holl, exhibiting a rather extreme form of the bushy type, is shown in Fig. 31. The lateral branches are few and are subdivided into a comparatively small number of very long filaments. The presence of eleven or twelve such axes, of which the gill is composed, in an area about 9x6 mm., produces the effect of a dense bush. The gills of nearly all the specimens of A. imsilla examined con- form to the pinnate type (c/. PI. XIII, Fig. 41). Those of massive examples (160 mm. long) of this species from Unalaska are, however, of different form (Fig. 32): the axes are proportionately very short (2 • 5 mm.) and bear on each side only three, or at most four, branches,. Please note that these images are extracted from scanned pa
Size: 2409px × 1037px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1912
