. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. Fig. 2. Willia mutabilis. The radial canal system of the earliest stage, showing four primary, perradial canals and four canals run- ning to the four interradial tentacular Fig. 3. Willia mutabilis. The radial canal system of an early stage, showing commence- ment of torsion of the umbrella; also a single branch to each of the eight radial canals. primary radial canals, whereas the four others are lateral branches of the former. Presumably therefore a still younger stage exists, with onl
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. Fig. 2. Willia mutabilis. The radial canal system of the earliest stage, showing four primary, perradial canals and four canals run- ning to the four interradial tentacular Fig. 3. Willia mutabilis. The radial canal system of an early stage, showing commence- ment of torsion of the umbrella; also a single branch to each of the eight radial canals. primary radial canals, whereas the four others are lateral branches of the former. Presumably therefore a still younger stage exists, with only four radial canals, as in young specimens of Proboscidactyla. In the third specimen of this sample a torsion of the umbrella has just commenced (Fig. 3); the course of the four primary canals is not exactly perradial in relation to the stomach, and the corresponding tentacles are a little displaced, in a clockwise direction when the medusa is seen from above. The four interradial basal bulbs have developed into tentacles which, however, are distinctly smaller than the four perradial ones; moreover, there is a lateral branch to each of the eight radial canals, issuing somewhat nearer to the umbrella-margin than to the stomach, all to the same side; at the termina- tion of each of these lateral branches is a very small basal bulb, and above each of these a cluster of nematocysts. There are several slightly older specimens in which the two radial canals issuing. 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 Institute of Oceanographic Sciences (Great Britain); National Institute of Oceanography of Great Britain; Great Britain. Colonial Office. Discovery Committee. London ; New York : Cambridge University Press
Size: 1587px × 1574px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
