Eyespot rasbora ventral area of the body between the operculum and the pelvic fins (corresponding roughly to the sac enclosing the alimentary canal). Under conditions of reflectied light, the fish sometimes displays a fine lateral band from the opeculum to the end of the caudal peduncle (Walker, 1971, p. 98) this being an olive-gold hue. The fins, with the exception of the dorsal fin, are hyaline, the relation of the pectoral and pelvic fins being typical of the ostariophysans (fishes possessing an auxiliary mechanism for detecting sound consisting of a set of internal bones called the Weberian Ossicles). In such fishes, the
Operculum (gastropod) seals the shell, it can also serve as a protection against predators when the snail body is retracted. In life, the operculum is attached at the ending of the columellar muscle with an opercular disc dorsally to the upper surface of the posterior part of the foot. However, in "Buccinum" a layer of long cylindrical epithelial cells, with mostly distinct nuclei, and long divided processes enter between the muscular fibres. The operculum, a cuticular development of these cells, is composed, as may be seen in the corneous opercula of "Murex", "Purpura", "Triton", of very thin superimposed layers. The cylindrical cells