. Handbook of zoology [microform] : with examples from Canadian species, recent and fossil :. Zoology; Invertebrates; Zoologie; Invertébrés. PROVINCE RADIATA. 85 Fig. C". I \ PLEunoBRACiriA iiiiODODACTYLA, (aftcr Ajfasaiz.) globular form, so slifjhtin Pleurobrachia as to be hardly per- ceptible to the casual observer, establishing two diameters of diflerent lengths at right angles with each other, is equally true of the other genera. It is interesting and important, as showing the tendency in this highest group of Acalephs to asBume a bilateral character. This bilaterality becomes still m
. Handbook of zoology [microform] : with examples from Canadian species, recent and fossil :. Zoology; Invertebrates; Zoologie; Invertébrés. PROVINCE RADIATA. 85 Fig. C". I \ PLEunoBRACiriA iiiiODODACTYLA, (aftcr Ajfasaiz.) globular form, so slifjhtin Pleurobrachia as to be hardly per- ceptible to the casual observer, establishing two diameters of diflerent lengths at right angles with each other, is equally true of the other genera. It is interesting and important, as showing the tendency in this highest group of Acalephs to asBume a bilateral character. This bilaterality becomes still more marked in the highest of Radiates, the Echiuo- derms. Such structural tendencies in the lower animala hinting' at laws to be more develo} ed in the higher forms, are always significant, as shewing the intimate relation between all parts of the plan of creation. This inequality of the dia- meters is connected with the disposition of parts in the whole structure, the locomotive fringes and the vertical tubes con- nected with them being arranged in sets of four on either side of a plane passing through the longer diameter, shewing thus a tendency toward the establishment of a right and left side of the body, instead of the perfectly equal disposition of parts around a common centre, as in the lower Radiates. " The Pleurobrachiai are so transparent, that, wiui some preparatory explanation of their structure, the most unscien- tific observer may trace the relation of parts in them. At one end of the sphere is the transverse slit that serves them as a mouth; at the opposite pole is a small circumscribed area, ''I. 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 Dawson, J. W. (John William), Sir, 1820-1899. Montreal : Dawson
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1870
