Elements of Comparative Anatomy (1878) Elements of Comparative Anatomy elementsofcompar78gege Year: 1878 122 COMPAEATIVE ANATOMY. § 96. In those Medusae wWcli have no longer any relation to Hydroids, the generative matters are formed in the wall of the gastro- vascular system, just as in the Medusfe of the Hydroid-Polyps, and the Siphonophora. These matters are generally formed in the radial canals (2Equorida3), or in the pouch-like diverticula of the stomach (^ginidee). When the canals are narrow the genitals form freely projecting diverti- cula, which, when much de- veloped, may have the fo
Elements of Comparative Anatomy (1878) Elements of Comparative Anatomy elementsofcompar78gege Year: 1878 122 COMPAEATIVE ANATOMY. § 96. In those Medusae wWcli have no longer any relation to Hydroids, the generative matters are formed in the wall of the gastro- vascular system, just as in the Medusfe of the Hydroid-Polyps, and the Siphonophora. These matters are generally formed in the radial canals (2Equorida3), or in the pouch-like diverticula of the stomach (^ginidee). When the canals are narrow the genitals form freely projecting diverti- cula, which, when much de- veloped, may have the form of ruff-like folds. The radial canals foi'm lamellar enlargements intheGeryo- nidae, when the generative matters are developed. In all forms the lower wall of the canal, or that placed away from the umbrella, forms the genital region (Fig. 35, f/). The germinal matters in some cases reach the exterior through the stomach, and in other cases by a rupture of the tissue. In the Discophora the generative organs have always much the same re- lations, and differ but little in position and form. They consist of four or eight frills, curved in a semi- lunar form, and arranged in a rosette on the inner surface of the umbrella (cf. supra. Fig. 44, ov) ; the frills are formed by diverticula of the gastrovascular system. They are placed in depressions on the lower surface of the disc, or hang fi-eely down from it, often in numerous folds. The Lucernarife have the generative organs in the form of eight radially-arranged longitudinal ridges, placed on that part of the body which corresponds to the sub-umbrella of the Meduste, where they form projections into the pouches of the gastrovascular system. They represent, therefore, an intermediate form between the Hydro- medusse and Discophora. rig. 49. Diagram of a radial vertical section through a sexually mature Geryonid (Carmarina hastata); on the right it is taken through the whole length of a radial canal, and on the left through the
Size: 1383px × 1446px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
